| 1. Engineering
Problems of the Proposed Underground Rapid Transit System in Taipei City from
the Point of View of Subsoil Characteristics
Mass rapid transit system is a necessity for any modern developed city to
alleviate the traffic problem and to provide the people in a large metropolis
with a smooth and time-saving transport system. The Government in the ROC is
actively planning on a Mass Rapid Transit System for Taipei City. This paper
presents a preliminary discussion on the geotechnical problems for any future
underground rapid transit system in Taipei. Discussions are made on: (1) effect
of regional subsidence of the Taipei Basin, (2) bearing capacity and settlement
of underground structures, and (3) effect of construction of underground system
on neighboring existing structures.
2. Design
and Construction of Earth Anchors
This paper presents the current design methods and construction practice of
ground anchors. Reference is made to the suitability of using ground anchors
in the Taipei subsoil conditions. The need for proof test and monitoring system
is emphasized.
預力地錨 (prestressed earth anchor) 在土木工程上的運用大概有近四十年的歷史，其應用範圍包含了: 1. 邊坡穩定設施 2.
港灣岸壁結構之斜支系統 3. 乾船塢底部之上舉力抵抗 4. 樁載重試驗之錨定裝置 5. 深開挖護土設施之支撐 6. 建築基礎抵抗上浮力之錨定等等。近年來由於人類活動日漸趨向都市，都市中形成寸土寸金現象，土地之利用無不求其極致，在都市中建築皆求往高空或往地下發展，高樓建築為求基礎之稅固、經濟，常採深入地中之浮式基礎設計
(Floating Foundation)，因此建築施工常遭遇開挖工程甚深的難題，深開挖工程安全保証措施所採用之支撐系統，除傳統式內部支撐外(Internal
Bracing)(如圖1-a.)，尚有利用此種地錨者即所謂之背拉系統(Tie-Back), 前者於開挖面內部利用木樑或鋼樑支撐，以抵擋由護土設施傳來之土壓力，內部支撐之優點在開挖面積及深度皆小時裝設迅速，成本較低，其缺點為開挖面積甚大時，因橫樑過長易生挫屈
(Buckling) 以及變形(Deflection)，造成危險，開挖深度過深時，需多層支撐，則裝設費時困難．同時對開挖工程之挖土、出土形成干擾，延長施工時間，增高了施工的成本，也同時降低了施工安全性．在目前世界各地大規模深開挖工程皆傾向於採用後者背拉法支撐系統(圖1-b)，背拉法乃利用鑽機鑽孔，穿過護土設施，並進入護土設施後側土壤中，再置入拉力鋼線灌漿，產生土中錨定(Earth
Anchor)作用，利用此錨定力拉住護土設施，產生支撐效果，此法可使整個開挖面完全開放，挖土出土極為便利，使開挖工作迅速進展，縮短工期，相對的提高安全性，其缺點在至於施工材料如鋼線等不似內部支撐之鋼樑可重覆使用，因而成本較前者為高，但若就總工程費而言，在開挖面積及深度，超過某一限度時，反而要較前者為低，背拉法在台灣原有許多工程曾先後採用，唯因少數工程設計及施工不當發生問題後，造成目前許多工程不敢採用．主管當局不敢核准等現象，殊為可惜，在國外已有工程採用背拉法施工，開挖深度達地下33公尺者，目前台灣工程界對此法裹足不前，豈非因噎廢食，其實背拉法之設計若能與設計原理及士壤性質有詳盡的了解，對裝設工程有良好的管制，其效果絕不亞於內撐法，在許多種情形下甚至較內撐法更有效。因此本文乃希望針對深開挖工程地錨系統之設計及施工應注意事項作概略的介紹，期能使工程界獲得了解，打破心理障礙，慎於採用，則亦是一件值得慶幸的事。
3. Site
Investigation and Soil Testing-Purpose, Methods and Application
This lecture introduces the purpose, methods and application of results of
site investigation and soil testing in civil engineering work. Emphases are
placed on the adequacy, correctness and quality of site investigation work
with illustrations. Problem of "false economy" is discussed. An analogous
comparison is made between the roles of a geotechnical engineer with that of
a medical doctor.
在一件土木工程中負責設計的工程師通常需要做兩個作業，首先他必須能夠預測 (Prediction)在建造過程中可能發生的問題及完成後該建造物是否能附合所需，第二他必須有能力根據他的預測來作判斷及決定。土壤及岩石為自然的產物，其性能變化甚大，並且有時很複雜。土壞的性能隨時間、壓力、水份變化、及環境更改而變化，因此土壤及基礎工程師所須做的預測更為複雜，同時也更難準確。
4. Design
and Construction of Deep Excavation
Discussions are presented on the procedures involved in the design and construction
of deep excavation works. Commonly used methods for estimating earth pressures
and design of retaining structures are presented. Comparisons are made on the
advantages and disadvantages of various types of earth retaining structures
with particular emphasis on the conditions in the Taiwan area. In the discussion,
emphases are placed in the importance of obtaining correct and sufficient subsoil
information prior to planning and design, and the necessity of strict control
during construction. Use of Instrumentation for construction monitoring is
introduced.
在今日工程建設高度發展的時代，工程的施工幾乎無可避免的必需要遭遇到深開挖(Deep Excavation)的問題，所謂深開挖，根據Terzaghi(1948)之定義為超過20英呎，即6公尺深之開挖工程皆屬之，一般而言需要深開挖的工程包含了:
1．高樓建築物地下室之施工 2．公共管線如下水道系統或地下電纜等 3．多層地下停車場之建築 4．地下捷運系統 5．山區公路系統甚至如 6．山坡地開發時之邊坡垂直開挖等等工程，無一不需面對相當深度之開挖工程，自然就經濟觀點而言，在空間及土壤強度許可下，開挖工程希望能在不需要任何保護設施之情形下進行，但此種情況對深開挖之情形常不可能，因為深開挖工程通常進行時間較長，而為保持穩定，採取自然穩定坡開挖時，勢必增加大量土方，反而使得工程經費增加成為不切實際，因此在遭遇深開挖工程時，通常設計必需針對下列幾項原則進行:
1. 必需能防止工程本身之破壞。 2. 保護設施應能兼顧及開挖工程鄰近建築物之安全。 3. 保護系統之裝設應能配合施工之進行，並且不造成對其他施工工作的過分阻礙。
4. 必需能儘可能節省經費，保持經濟性。因此原則上深開挖的設計工作，除了應滿足安全約需求外，尚應考慮經濟要素，並將施工環境條件均考慮在內，本文即針對深開挖工程之設計及施工要點提出，以為一般設計者之參考。
5. Effects
of Soil Structure on Compressibility of an Artificially Sedimented Clay
The purpose of this research is to investigate the effects of soil structure
on the one-dimensional consolidation behavior of a silty clay. Clays with different
soil structures were produced in the laboratory by using different fluids for
sedimentation, namely, a calcium chloride (CaCl2) solution, a sodium metaphosphate
(NaPO3)x solution, and fresh water. In addition, the effects of reduction in
the pore fluid salt concentration due to leaching on consolidation behavior
of marine clays were also Investigated.
6. A
Method for Determining the In Situ K Coefficient
Most of the available testing methods for determining the coefficient of earth
pressure at rest give only "apparent" value. A new testing method
on the basis of a different concept has been developed for the determination
of the "in-situ" coefficient of earth pressure at rest for clays
in laboratory. Results of experimental investigation indicate that the proposed
method is reliable and can be applied to both normally consolidated clays and
lightly overconsolidated soils.
7. Effect
of Leaching on undrained Shear Strength Behavior of a Sedimented Clay
Leaching is one of the major environmental changes which could occur to a
marine clay post deposition due to seepage of rain water and/or flood water
through the soil. Reduction of salt concentration in the pore fluid of a clay
upsets the balance of the interparticle electrical forces and the particle
alignment, which results in instability of the soil structure. A laboratory
experimental Investigation was carried out to study the effect of leaching
on the shear strength behavior of a sedimented clay from the Bangkok area.
Artificially sedimented samples were prepared by sedimenting the clay in sodium
chloride solution and then leached with fresh wafer to various final salt concentration.
Laboratory vane shear tests and isotropically consolidated undrained triaxial
tests with pore pressure measurement were performed on the leached samples.
Test results showed that leaching of the salt concentration Increased the soil
sensitivity. Both the undrained shear strength and the effective angle of shearing
resistance decreased with leaching.
8. The
Current Practice of Liquefaction Analysis in Taiwan
Taiwan is located in the region with high intensity of seismic activities
where numerous server earthquake disasters have been experienced. Most the
important engineering projects which are to be founded on loose sand subsoil,
liquefaction potential analysis in response to a design earthquake intensity
is usually carried out during the designing stage. This paper reviews the current
method adopted in some of these projects. Due to insufficient of testing facilities
in Taiwan, a complete study on liquefaction potential has never been performed.
9. Landslides
in Taiwan Some Case Reports
Seven case histories of landslides are presented in the paper. These slides
are of the types which are common in Taiwan. The major causes for the slides
were either due to saturation of the soil mass after a heavy rainfall or due
to high pore water pressure developed in the subsurface strata. Preventative,
control or remedial measures adopted are described.
10. Engineering
Properties of Soils Using Rice Hull as Stabilizer
The study of an effective utilization of rice hull ash, which is produced
100,000 tons per year in Taiwan, becomes necessary. This study investigates
the uses of rice hull ash with lime as a soil stabilizer admixture. The primary
purposes were to study the compaction characteristics and the factors affecting
the strength development of the lime-ash stabilized sandy and clayey soils.
Standard compaction test and undrained direct shear test were carried out.
Results showed that adding rice hull ash into a soil increased the effectiveness
of lime. Lime-ash admixture caused the compacted dry density of a soil to decrease
but the as-compacted strength to increase. The shear strength of a lime-ash
stabilized soil increased with curing time, but reduced when soaked. The optimum
lime-ash weight ratio of soils was found to be 1:2 or 1:3. To produce equivalent
strength values, the percentage of lime requirement could be reduced by adding
rice hull ash.
臺灣每年廢棄稻殼灰數量達十萬公噸以上，如何有效利用，已是一項重要研究題。本文在研究利用稻殼灰與石灰混合作為土壤穩定劑，並在瞭解其應用於砂質土壤及粘質土壤時之壓實特性和影響穩定後土壤強度之因素。實驗方式是採取標準壓實試驗及不排水直接剪力試驗。結果證明稻殼灰對砂質及粘質土壤均有增強石灰穩定效果之功能。滲加石灰和稻穀灰減低土壤之壓實乾密度，但增加土壤之壓實後強度。穩定後土壤之強度隨養治時間而增強，受吸水而降低。各土樣之石灰及稻殼灰最佳重量比是1：2成1：3。欲得同樣之穩定強度，使用稻殼灰，可節省石灰之用量。
11. Emergency
Rehabilitation of Concrete Pavement Section of an Airport Runway
The E-W runway of the Taipei International Airport was constructed some 20
years ago. Due to heavy usage and poor subgrade condition underlying the runway,
certain critical sections of the concrete pavement have deteriorated badly
and required urgent replacement. The most critical requirement for the replacement
work was that the runway must be kept in operation every day. Less than seven
hours per night was available for the construction work. All operation including
removing of the damaged pavement, replacing subbase, compaction of subgrade,
placing and curing of the new concrete must be completed within this short
time period. This paper describes a successful design and construction procedures
adopted for such an operation in 1976.
12. Design
and Construction Practice of Slopes in Hong Kong
This paper presents a general discussion on present design concepts and construction
practice of slopes in Hong Kong. Stability analysis of a soil slope using a
computer program and a rock slope by stereonets are illustrated. The extent
and general requirements of site investigation for slopes are presented. In
construction practice, surface protection methods such as chunam plastering
and guniting for soil slopes and anchors for retaining rock wedge are discussed.
Particular emphasis is made to Government requirements on geotechnical consultancy
on design and construction supervision of geotechnical related structures.
13. Slope
Problems in Sandstone and Shale Formation
In the island of Taiwan, over four-fifth of the land area is hilly or mountainous.
Due to the limited availability of plain areas, utilization of slope land for
housing and industrial development becomes more popular in recent years. Problem
of slope stability is the utmost important consideration for these developments.
Many slope failures or landslides have occurred in the past few years. Geologically,
about one-fourth of the total land area in Taiwan is composed of interbedded
sandstone-shale formation. They are distributed in the Western foothill region
of the island where numerous faults are also concentrated. This paper presents
the engineering characteristics of the sandstone-shale formation in Taiwan.
Discussions are presented on the causes of landslides and special characteristics
of slopes composed of this type of formation. Methods of slope stability investigation
and design are also described.
本省面積五分之四屬於山嶺或丘陵。近年來人口激增，有限之平原地區已不敷使用，活動居住範圍漸向山區擴張，因而山坡地之開發，日漸普遍。開發山坡地、邊坡穩定問題當為首要之安全顧慮。綜觀本省之山嶺或丘陵地區，地質構造層於砂岩與頁岩互層者頗廣，概略估計約佔本省總面積四分之一，分佈在中央山脈與西部海岸平原間之麓山帶，從北延伸至南，如圖一所示。砂頁岩分佈區域，不幸亦為本省斷層密集區，因此，山坡地開發上,砂頁岩之邊坡穩定問題，尤應特別汪意。近年來砂頁岩邊坡崩坍之例頗多，漸為工程師所重視。本文主旨在介紹本省砂頁岩之工程性質，進而研討此類邊坡之崩坍原因及特性，穩定調查方法及設計要點。
14. Engineering
Characteristics of the Taipei Silt
The Taipei Basin was formed some hundreds years ago by a series of sedimentation.
The primary subsoils in the Basin are alternative stratum of silt, silty clay
and fine sand. The silty and silty clay layers are highly compressible and
of low strength. The virgin watertable is very close to the ground surface
and presents above the upper silt layer. In recent years due to heavy deep
well pumping, the groundwater appears to be separated into two distinct zones,
with the upper part appearing to be a perched watertable above the silt stratum
and the lower zone dropping into the fine sand stratum below the silt. The
piezometric levels in the silt layer become less than the static pore water
pressure. This effect has led to problem of serious regional subsidence. This
paper presents a discussion on the engineering characteristics of the Taipei
Silt in particular reference to its effect on the design and construction of
foundations and other geotechnical structures.
15. Design
and Construction of a High Retaining Scheme
A multi-storey factory building is proposed to be built on a site 90 m long
by 50 m wide, in a congested industrial area in Kowloon, Hong Kong. The site
situates at the bottom of a hillside with a highway at the mid-level of the
hill. In order to maximize the utilization of the site area, it is necessary
to have very steep cut along the backside of the site. A retaining scheme consisting
of anchored caissons and curved laggings was designed. Due to the difficult
site condition, instrumentations including inclinometers, piezometers, pressure
cells and anchor load cells are installed for construction control and long
term monitoring. This paper presents the results of site investigation, design
and construction of the retaining scheme which is currently in progress. The
total cost of the site formation and retaining scheme is estimated to be around
US$2.4 millions.
16. General
Report Technical Session I : Stress-Deformation and Strength Characteristics
Including Soil Dynamics
The purpose of a general report is to provide a review and critique of the
papers presented in a session. The 24 papers assigned to session I of this
Conference on Stress Deformation and Strength Characteristics (including Soil
Dynamics) covers a wide range of topics. Most of the papers are not related
to each other and they do not fall into groups. To give a critical review of
all the papers in this Session will almost require to write comprehensive treatises
on several subjects. The State-of-the-Art of Stress Deformation and Strength
Characteristics up to the year of 1976 has been critically reviewed and excellently
presented by LADD et al in their paper presented at the Ninth International
Conference on Soil Mechanics and Foundation Engineering in Tokyo in 1977. Although
there are a large number of papers which have been published on this subject
during the last two years, there appears to be no new break through. This report
will attempt to assemble the 24 papers in this session in an orderly manner
and to summarize the salient contents so that the participants can select papers
of interest for more detailed study. The 24 papers can be broadly divided into
the following four groups: (1) Behavior of cohesionless soils - 9 papers (2)
Behavior of cohesive soils - 6 papers (3) Evaluation of soil parameters - 5
papers (4) Soil dynamics - 4 papers
17. Building
Foundation Practice in Taiwan
18. Liquefaction
Potential Study for a Power Plant Site
This paper presents the results of a soil liquefaction potential study for
a proposed power plant site. Soil liquefaction potential analyses were carried
out by means of semi-empirical methods, analytical method and effective stress
analysis. Evaluation of results of analyses show that localized liquefaction
could occur at the proposed site when the ground motion acceleration is equivalent
to or higher than 0.13 g. Compaction sand piles were recommended to be used
to density the sand deposit. The results of densification of the loose soil
after installation of compaction sand piles are also reported.
19. Pressuremeter
Method for foundation Design in Hong Kong
The use of pressuremeter to measure the deformation characteristics of completely
weathered granite in Hong Kong for the design of substructures are described
in this paper. Correlation between pressuremeter moduli and limit pressures
from pressuremeter tests and N-values from standard penetration tests are made.
Bearing pressure calculated from pressuremeter modulus is compared with those
computed with N-values. Values of coefficient of modulus of weathered granite
for calculating lateral resistance of deep foundations are reported.
20. Plugging
of Open-End Steel Pipe Piles
The use of steel pipe piles gradually becomes more popular in recent years.
One of the major advantage of steel pipe is the high strength of pipe material
itself. In design, maximum utilization of the steel strength is usually considered.
However, the actual design capacity is often affected by the buckling strength
of the pile during driving. In order to reduce driving resistance, open end
pipe piles are often used. Steel pipe piles derive its bearing capacity from
both side friction and end bearing. For open-end piles, if a dense plug could
be formed inside the pipe after driving, the pile will behave similar to a
closed-end pile as far as end bearing is concerned. It is thus obvious whether
a good plug is formed or not has enormous effect on the bearing value of the
pile. This paper describes a case record of driving open-end steel pipe piles
through soft clay layer. Properties of the plug formed inside the pipe were
examined. The bearing capacity of this type of piles was compared with closed-end
pipe piles by full scale loading tests.
21. A
Case Study on Improvement of a Vibrating Foundation
Three oxygen compressors supported on piles were found suffering too severe
vibration amplitudes that improvement of the foundation is required. This paper
describes a complete case study of analysis and improvement. The original design
of the foundation and the soil properties at site are reviewed. Based on a
soil-pile interaction analysis, the computed vertical, sliding and rocking
mode of vibration were compatible with the actual measured amplitudes. The
method of improvement for the foundation Is designed according to the required
criteria. Improvement of foundation involves installation of additional .piles
with an enlarged footing. Comparison of the predicted results with the measured
vibrating amplitude after improvement is made.
22. Instrumentation
for Deep Excavation Monitoring - A Case Study
Due to the variable nature of soil behavior in situ, many soil engineering
design have to use greatly simplified soil condition and to employ idealized
assumptions. It has long been recognized that field performance records play
a vital role in the improvement of the state-of-the-art of soil engineering
practice. Use of field instrumentation for monitoring soil engineering construction
has become more and more popular in developed countries. The contribution of
instrumentation to construction safety cannot be overemphasized. In Taiwan,
deep excavation for building construction becomes a common practice In the
last few years. However, either due to improper design and lack of sufficient
knowledge of soil behavior, many problems, even to the extent of complete failure,
have occurred during excavation work. This paper describes one of the first
project in Taiwan using field instrumentation for monitoring deep excavation
of a tall building structure. Instrumentations installed at the site include
inclinometers, piezometers, heave points and settlement points. Field monitoring
data in relation to the construction progress are analyzed and discussed.
23. Site
Investigation of Maanshan Nuclear Power Plant in Taiwan
The third Nuclear Power Plant of R.O.C. is located at Maanshan in the southern
tip of the island of Taiwan. Previous geological Investigation indicated the
possible presence of a fault near the proposed location of the power plant.
Since Taiwan is situated in the circum-pacific earthquake belt, site selection
and design of foundations for the Nuclear Power Plant require extremely careful
investigation. The site investigation program for the Maanshan Nuclear Power
Plant was performed in stages, which included drillings, sampling, exploratory
trenches, test pits, geophysical survey, field instrumentation, and various
types of laboratory tests. Results of the site investigation for power block
area are presented in this paper.
24. A
Study on the Causes of Some Rock Slope Failures along Highway in Taiwan
Geographically, the terrain of the island of Taiwan is mountainous, many highways
cut across hillsides of soft rock formation. In the last few years, numerous
rock slope failures occurred alone highways causing serious obstruction to
traffic and sometimes loss of life. The causes of failures can be grouped as:
(1) types of geological formations, (2) heavy rainstorms, inducing high pore
water pressures in the soil or rock formations, (3) reduction of strength and
swelling, of soft rocks due to adsorption of water, (4) weathering of unprotected
or inadequately protected slope surface, (5) improper design and/or construction,
Generally, a slope failure may be attributed to one or a combination of several
of the above mentioned causes. This paper presents a detailed discussion on
these causes of failure with particular emphasis on the sandstone-shale formation
commonly occurred in Taiwan. Several case studies of rock slope sliding are
reported.
25. Compaction
Sand Piles for Soil Improvement
At the site of a steam power plant in the southern part of Taiwan, the top
6 in of the subsoil is a loose fine sand deposit which has high liquefaction
potential. Since the power plant is located in a seismic active zone, it is
necessary to improve the subsoil condition by densification. Compaction sand
piles of 45 cm diameter, 7.5 m long placed at 1.8 m. center to center spacing
in a triangular pattern distribution were used. The area being improved in
the first stage of construction is 3,500 sq m. For the evaluation of the effectiveness
of the improvement, soil sampling and Standard Penetration Tests were performed
at random locations both prior to and after the improvement. The test results
indicate that the improvement is successful, with 100% samples giving over
the required 65% relative density, and 92% samples with more than 75% relative
density. Standard Penetration Tests were found to he an effective way for the
field control work. Correlation between the SPT values and relative density
was established.
26. The
Deflection of Earth Retaining Diaphragm Wall during Deep Excavation
The technique of constructing rein forced concrete diaphragm wall together
with internal bracing or tie-back system in deep excavation has been practiced
for many years. It has become one of the most popular earth retaining schemes
for deep excavation nowadays, yet the analytical methods on the lateral displacement
and deflection of the diaphragm wall are still in vague and a sort of art.
This report describes a simple spring model method to predict the lateral displacement
and deflection of the diaphragm wall in according to sequence of excavation.
A scheme of selecting proper soil strength parameters and earth pressure diagram
as well as determination on the soil spring constants is introduced. Direct
measurements on the lateral movement of the diaphragm wall has been carried
out in site during deep excavation. The results demonstrated that the prediction
for lateral movement of the diaphragm wall by the spring model method has a
reasonably fair accuracy.
27. Engineering
Problems of Gravel Deposits in Taiwan
The primary terrace deposits on the-island of Taiwan are gravels, with distributions
spread out along the western edge of the northern and central part of the island,
as well as in areas between the coastal- plain and foothills. Due to the rapid
economic development and population growth on the island in recent years, areas
of activities are inevitably moving towards slopelands and hillsides. Many
highways, residential developments and industrial zones are situated on terrace
deposits. Since the geotechnical characteristics and behavior of terrace gravel
deposits are significantly different from those of alluvial and sedimentary
deposits or rock formations, selection of methods of "exploration, testing
and analyses often poses problems to geotechnical engineers. The most commonly
encountered problems or difficulties include: (1) Which method(s) is most suitable
for site investigation of gravel deposits? (2) How to determine or analyze
the slope stability of gravel deposits? (3) What is the bearing capacity of
a gravel deposit? How much is the settlement of structures founded on this
type of deposit? Up to the present time, study of engineering behavior of gravel
deposits in Taiwan can only be considered in the infant stage. Many of the
basic data are still lacking. The primary objective of this paper is to present
a rational approach to exploration of the engineering behavior of gravel deposits
in Taiwan, on the basis of geological history, particle structure and limited
engineering experience, with particular emphasis on slope stability and foundation
problems. It is hoped that this paper will stimulate the interest of the geotechnical
profession in the engineering problems of construction on terrace gravel deposits.
28. Underground
Diaphragm Wall Construction by BW Technique for Supporting High Rise Building
The construction technique of diaphragm wall in slurry trench has been used
extensively all around the world for the past two decades. Earlier applications
of diaphragm walling were most of all limited to such circumstances as when
the accuracy and quality of wail was not essential, i.e., underground cut-off
for seepage protection and temporary retaining wall for deep excavation. Recently,
with new techniques and equipments having been developed for excavating trench,
and along with many different engineering disciplines, the wall could be built
with higher degree of precision; therefore, this kind of wall is capable of
being accomplished into permanent structure or even as well as bearing element
for Supporting the building load. It is known that quality of concrete wail
rather depends upon slurry control during tremie concrete process; nevertheless,
the equipment used for trenching is important both in maintaining the high
degree of verticality and consequently the quality of the final product. In
the present market, more than 15 types of diaphragm wall excavation machines
using various arrangements of cutting processes are available, such as conventional
type of clam-shell bucket or chisel, scraper bucket type Else machine and rotary
driller. This report concentrates on the unique rotary drilling equipment developed
by Tone Boring Co. of Japan for trench excavation in slurry with reverse circulation
operation to remove cutting soil. When the wall is designed to be incorporated
into permanent structure, details of joint system, reinforcement connection
and some requirements in the specification preparation are also recommended.
29. The
Practice and Recent Development in Foundation Engineering of Tall Buildings
The paper discusses recent development on deep foundations and compensated
foundation systems for tall buildings. Problems associated with deep excavation
are also described.
高樓建築物由於其特殊高度、強度、環境等因素，在基礎工程方面需要特殊的考慮。自基礎工程設計觀點視高樓建築，有下列特點: 1. 高度集中荷重-由高樓經由樑柱累積傳達至柱腳之集中荷重相拈當大，於地震或風力作用情況而生之偏心荷重傾倒力矩亦高
2. 極大不均勻載重--為了美觀及實用，在高樓四週常環繞一些五至六層的低層建築，因此低層建築之荷重量與高樓形成強烈之對比。因此，基礎設計時必須考慮下列因素
: 1.基礎土層之安全支撐能力--必須能保證在高度荷重下，建築物亦不致傾覆，並且地震時也不會發生局部超壓破壞。2不均勻之沉陷量--高低樓間重量差異甚大，但在功能上卻必須銜接，因此在設計時，要考慮到由於荷重差異而可能發生之不均勻沉陷量.
如何消除此一不均勻沉陷量，常決定了基礎形態。3.施工之限制--由於高樓建築工程泰半在都市中進行，因此施工時有許多限制，例如 : 噪音、交通、污水等。高樓建築的基礎設計就必須配合這些施工因素，以求在這些限制下順利完成基礎工程。4.工期及管理--為了爭取時間，在施工時常希望高樓的主體部分能迅速完成，而環樓之低層構造可稍後開工以配合全部工期。因此基礎工程的設計，也要考慮各時期的施工安全，以最理想之基礎設計來爭取施工時效。同時也需特別注意高樓建築基礎受力情況之特殊性質，在施工過程中，初期與末期間作用於地層上壓力差距極大，應力在地層中如何重新分配，即所謂結構物興土壤之互制作用(Soil-Structure
interaction)，亦為高樓結構基礎設計的主要研究項目之一。因此在高樓基礎設計之前，需有充分的地質分析資料，諸如土壤支承特性、沉陷量、可能之差異沉陷，對地震、風力所生之側壓影響
30. Moderator's
Report on Soil Improvement
The basic concept of soil improvement-densification, cementation, reinforcement,
drainage, drying and heating although were developed hundreds and thousands
of years ago, they still remain valid today. Tremendous progresses have been
made in recent years In the development of techniques or methods for soil improvement.
Today, there are hundreds of methods, many of them are patented, available
on the market for improving or rather changing properties of soils and rocks.
Some of these methods or techniques are well developed and have sound theoretical
basis, many of them, on the other hand, are still very empirical. Professors
James Mitchell and R.K. Katti (1981) have presented a well documented State-of-the-Art
report on the subject of Soil Improvement at the Tenth International Conference
on Soil Mechanics and Foundation Engineering held in Stockholm in 1981. Since
then, a number of papers have appeared In various literatures reporting case
histories and new development of soil Improvement techniques. At this conference,
there are a total of 7 papers on the subject of soil Improvement. They Include:
one on preloading with compaction piles, one on sand drains, one on grouting,
one on using lime as admixtures for stabilization, one on lime migration piles,
and two on vibro-replacement-stone columns. Starting from the coming Monday,
29th November, a special symposium and short course on the Improvement of Soils
and Rocks will be held in Bangkok under the joint sponsorship of the Asian
Institute of Technology and the Southeast Asian Geotechnical Society. A large
number of papers are going to be presented and discussed. For my report today,
due to time limitation, I will only present a general summary of soil Improvement
methods which are currently in use and then followed with short descriptions
of four case records.
31. Preloading
of Foundation Soils for Oil Storage Tanks
One 10,000 kl and seven 50,000 kl capacity oil tanks are to be constructed
in south-western part of Taiwan. A detail geotechnical investigation was carried
out. It was found out that the subsoils at the proposed tank site are mainly
of silty sand, clayey silt and silty clay with thin layers of fine sand. In
order to improve the bearing capacity and compressibility of the subsoils,
a preloading scheme was used along with field instrumentation monitoring for
evaluating the effectiveness of the soil improvement. Subsoil properties were
greatly improved resulting significant saving in construction cost by adopting
the preloading scheme.
七座直徑61公尺高度18．3公尺之五萬公秉油槽與一座直徑36．6公尺．高度12．2公尺之一萬公秉油槽，建立於臨海地區之沖積平原上，經詳盡的地基探查結果顯示，此沖積平原主要為沉泥質砂層及粘土質沉泥或泥質粘士夾細砂薄層組成。經採用預壓方式之土質改良來減少油槽使用時之沉陷量，以達到油槽基礎穩定及槽體之安全。為了解並檢核預壓期間土質之變化，於預壓前裝設沉陷板與壓氣式水壓計觀測系統儀器，並於槽體完工試水試驗之前於槽體四周設置沉陷觀測點進行觀測，按兩階段之觀測結果顯示與原有分析結果極為接近，此亦證實若有群細的地質調查資料，並經合理的研判當可獲得經濟之油槽基礎設計。
32. Site
Investigation and Design for Slopeland Development - A Case Study
Owing to the rapid growth of population and development in Taiwan, the available
flat land area is becoming more limited and the development on the hill side
is a natural tendency. However, some conditions must be observed in the hillside
development. Since Taiwan is located at the circum-Pacific seismic zone, it
has many faults and fractured strata, with its raining climate, serious erosions
and landslide will be a serious problem. Many hill area development had failed
during the past few years because of the negligence of basic geotechnical information
and engineering design concept. This paper describes a case study about the
engineering concept on the development of hill area at Hsintien in the .suburb
of Taipei. A well integrated engineering plan which includes field investigation
and basic information collection, preliminary design plan, detail design plan,
construction and maintenance plans, is a required for a successful hill area
development. The paper emphasizes on the special consideration on the safety
and economy in hill area development.
由於台灣人口與經濟之快速成長，使得呵利用之平地空間已漸不敷使用，故坡地開發工作已是台灣土地利用必然趨勢。惟台灣位於環太平洋地震帶、富斷層及破碎帶、氣候多雨、滑移沖刷嚴重。近年來坡地開發失敗案例層出不窮，政府及工程單位檢討其主因乃是忽視坡地調查資料之重要性與缺少工程設計基本因素之考慮。本文以新店塗潭里坡地開發為實例，說明坡地開發應有整體妥善之工程計劃；既由基地調查工作之執行與資料整理、基地初步規劃及建議、工程細部設計、至工程施工計劃建議與維護建議。尤其強調坡地工程調查、設計、及施工應特別考慮之因素，以符合工程安全經濟之原則。
33. Vibroflotation
- An Introduction
振動揚實法(Vibroflotation)為改良深層疏鬆砂質地盤，以增加土壤支承力，減小基礎沉陷量，與降低土壤液化潛能所使用之工法。此技術於930年代在法國發展，首先應用於建築物之基礎土壤改良，1940年代引入美國，1950年代再傳進日本，臺灣地區則在1970年代才開始採用此工法。工法之優點為：
(1)地盤改良效果均勻。 (2)在地表下8公尺內之深度均可施工，最大改良深度至地表下35公尺左右。 (3)施工作業不受地下水位之影響。 (4)改良後土壤之壓縮性降低，並可防止不均勻沉陷。
(5)所需工期短，施工安全性高。缺點為： (1)對砂質地盤之改良效果較彰。惟若細料含量超過40%，很難達到改良之效果。對於細料含量少於15%之砂質地盤，效果最好。
(2)現階段之施工深度仍受到限制。 (3)振動揚實法之振動為水平振動，一般振動機無法使用，且故障率高。
34. The
Design Approaches and Specifications of Diaphragm Wall
地下連續壁之應用早在1946年即已開發，早期多半用於水壩之截水牆(Cut-off wall)，截水牆之目的僅在於地下鑿出一溝渠，回填以混凝土或泥漿與混凝土混合液以造成一透水性甚低之薄膜以達成阻水效果，由於其主要目的僅在止水，因而對牆面之垂直、平整度、混凝土與穩定液之混合限制以至混凝土強度之要求較不嚴格，主要控制僅在水密性而已，較高精度之連續壁設計與施工之控制，在世界工程界中還是最近十年中由於建築工程深開挖中大量運用而被重視，在我國建築工程中，於1971年台北市吉林路中國國際銀行大樓工程中首次使用，由郭茂林建築師事務所設計，榮民工程處負責下工，採用日本利根製造之BW5580機，完成厚度55公分，深度15公尺之連續壁，完工面積達1619平方公尺，該工程將連續壁分成48個單元施工，其中45個單元順利於53個工作天內完成，不但是我國建築工程上之創舉，更是東南亞地區首先完成之地下連續壁，自此工程以後，國內建築工程界對地下連續壁漸有認識，施工能力漸增，至1970年代末期，幾達可謂對地下連續壁迷信之程度，以為使用連續壁則深開挖之施工絕無問題，事實上，地下連續壁為擋土設施之一種應考慮深開挖工程之一環，不但本身應有嚴格之施工控制，其設計亦應考慮開挖工程各階段變化，否則仍將導致工程之失敗，近年來由於施工監測工作之發展，獲得甚多施工過程之資料，使不論國內外對地下連續壁之認識加深，亦使得設計理論漸有進展，固然目前連續壁設計理論仍在發展階段，惟無流一之理論，為求我國工程界在此方面之發展，本文就現有之設計理理及設計應注意事項作一整理，以為工程界之參考。
35. Instructions
for Deep Excavation
This paper presents a brief description on the principles and use of instrumentations
for deep excavation monitoring.
一個重要的工程計劃，不僅動用了可觀的資源而且關係到環境的安全與人民生活品質的變化。一般而言，國內建築業者目前對於高樓建築規劃設計階段所需的先期地質調查分析的重要性已經普遍認定，但是對於施工階段開挖後的地質調查及安裝觀測儀器進行分析與評定工作的必要性尚難于以肯定。其結果往往是由於調查分析資料不足以成過份保守的設計，不但耗費工料而在施工時可能遭遇困難須作變更設計甚而造成工程事故的糾紛;或是調查單位進行不必要的詳細調查，徒然浪費錢財，甚至使收集到的資料未能合用或未必夠用，造成雙重的浪費。所以，深開挖工程在施工期間欠缺現場觀測資料收集以資分析判別工程安全的情況下，工程設計趨於保守就很平常況且保守設計的結果也未必安全。因此，為達到合乎安全與經濟的原則，深開挖工程設計觀測系統監測施工安全確實是有必要的。以下謹就設立觀測系統的原因、施工觀測項目及儀器系統的選擇要點提出，以為有關從業人員的參考。
36. Site
Investigation for Foundation Design in Soft Ground
The paper presents major concepts and methods for site investigation for construction
on soft ground.
國內近年來由於工業迅速發展，對工廠及建築用地需求亦相對提高，而如眾所周知，臺灣島嶼本身地質條件複雜，除山坡丘陵地外，平原地區僅佔全島面積約30%，而平原地區多屬新世紀之沖積地層，如臺北盆地屬正常壓密狀態之土層達約50公尺，在此種地層上興建構造物常需對地盤之承載能力與預期沉陷量均作適當考慮，再而選擇合適之基礎，而將來工程發展之趨勢，不但是工程規模的擴大，同時投資額亦大量增加，為加強經濟效益，工程的進度亦求其快速，因此在工程之設計及施工中任何疏忽都將導致財力及時間上大量的損失，此種情況在地質條件差的地盤上更易發生，於軟弱地盤上進行工程，事先必須有完善的調查，同時將結果正確的運用於設計與施工上，本文敘述調查的重點、原則及應注事項。
37. Investigation
and Analysis for Tall Building Foundation - Case Report
The paper presents basic principles and procedures for conducting site investigation
and soil analysis for design of tall building foundations. Discussions illustrated
by a case report include selection of foundation type, estimation of bearing
capacity, settlement, uplift pressure, stability and heaving during excavation.
臺北市近年來由於都市發展結果，建地取逐漸困難，故建築結構遂儘量向高空及地下發展。目前工程界有關高層建築基礎深開挖施工法雖已有多位學者著文發表，對高層建築基礎之形式選擇亦受普遍重視，但由於施工前對基地土壤調查不夠確實，土壤工程特性分析考慮因素不夠週密，仍不免有基礎開挖工程失敗的實例，氣不必要的浪費，有鑒於高層建築將漸形增加之趨勢，本文乃針對高層建築基礎土壤之調查及分析內容提出探討，以供基礎設計及施工者之參考。
38. Foundation
Selection for High-Rise Buildings
The paper discusses types and selection of foundation type for tall buildings.
高樓建築物基礎設計應特別考慮其特殊高度、強度、環境及施工等因素。高樓建築之特點在於: 1.荷重集中--高樓經由樑柱傳達相當大之集中荷重至基礎面上。
2.載重不均勻--為了美觀及實用，在高樓四週常圍繞一些五至六層的低層建築，因此低層建築之荷重量與高樓形成強烈之對比。因此，基礎設計與一般低層建築不同，必需考慮下列因素:
1.基礎土層之安全支撐能力--除保證在高度荷重時，建築物不至傾覆外，必須考慮地震時也不會發生局部超壓破壞。 2.不均勻沉陷量影響--建築物各部份基礎面接觸壓力差異甚大，因此在設計時，需考慮差異荷重而可能發生之不均勻沉陷量。而就高樓建築而言，基礎形態常受沉陷因素所控制。
3.工期及管理--為了爭取時間，高樓的主體部份需早期開始，而環樓之低層構造可稍後開工以配合全部工期。因此基礎工程的設計應配合工期並考慮各時期的施工安全，以最理想之基礎設計來爭取施工時效。因此高樓基礎設計需有充分的地質分析資料，諸如土壤支承特性、沉陷量、可能之差異沉陷、對地震、風力所產生之側壓影響、施工期間基礎面之應力變化、基礎形式對施工之影響等，均應有完善的分析，以達理想設計。本文就高樓基礎設計之選擇基本考慮因素作一介紹。
39. The
Influence of Distribution of Ground Water Level and Ground Water Pressure
on The Foundation Engineering in Taipei Basin
Since 1946, due to development of the metropolis, deep well pumping has been
used to augment water supply of Taipei City. The subsurface water level has
been found to decrease rapidly and the pore water pressured distribution in
the water bearing layers appears to be non-static and ever separated into two
zones. As a consequence of the drop in the subsurface piezometric level, serious
regional subsidence occurs in Taipei Basin. The design of foundation system
as well as the construction will definitely be effected by the distribution
of the piezometric level. The subsoil condition within the Basin can be distinguished
in three major zones according to its nature of deposit; namely Tam-Shui River
deposit zone, Keelung River deposit zone and Hsin-Tien River deposit zone.
This study is based on the observation record taken over two years period on
nearly 60 piezometers and observation wells installed in these three zones
to present the variation and distribution of free water level and pore water
pressure in each subsoil stratum. The results indicate that the free water
level fluctuates between elevation +2 m and -0.5 m level from January to December,
and the pore water pressure head in the fourth layer is continuous to drop
with time. The non-static distribution of piezometric level may cause some
problems during the foundation construction.
臺北市近年來由於經濟發展結果，處處高樓建築如雨後春筍林立。其他之重要工程如污水下水道、輸水幹線、高架工程亦逐步施工，此類工程建設均涉及重要之基礎工事，而工程地點地下水分佈，水壓變化對基礎工程設計及施工具有重大決定性之影響。臺北市位於臺北盆地之中心，多年來由於過量抽取地下水之影響，地下水壓已非常態變化
，目前工程設計對水位之考慮仍以靜態水壓為依據，致使設計偏於保守，沉陷量、支承力等估計亦不準確，然因所有工程均限於其時間、經費，無法對工程地點水壓變化作長期之觀測，對水壓特性無法確實掌握。本文仍就臺北市內數年來裝設之多處水位觀測井、水壓計所獲得之觀測結果提出綜合分析，對臺北市水位變化與季節性之關係、水壓變化對基礎土層工程特性影響、基礎工程施工應有之考慮等提出評估與建議，以為土木工程設計之重要參考。
40. A
Case Study on Negative Skin Friction
The potential development of negative skin friction is one of the major concerns
to geotechnical engineers in designing pile foundations at sites where ground
subsidence due to long term consolidation of compressible subsoils is anticipated.
A full scale testing program and theoretical study was carried out to evaluate
the effectiveness of a special asphalt coated pile (NF pile) in reducing the
magnitude of potential negative skin friction. Loading tests were carried out
on a special coated steel pipe pile and an uncoated plain pipe pile. From instrumentation
installed on the piles, distribution of stresses and therefore skin friction
along the pile shafts under loading were determined. It was found that HF pile
was effective in reducing the potential negative skin friction by as high as
90 percent.
41. Uplift
Resistance of Driven Concrete Piles in Sandy Soil
The paper discusses uplift resistance of driven concrete piles in sandy soils.
Analyses are presented on field test results of three sets of pulling tests
of concrete piles.
當樁被用於受上揚力作用或承受相當大傾覆彎矩之結構物，如地下建築物、煙囪、輸送塔、防波堤等之下部時，都必須抵抗外力加於其上之拔起力。拔起抵抗力之不足有如承載力之短缺，均可能發生結構之全盤破壞，其大小並不一定與樁在受壓情況下之承載力有直接關係。單樁之拔起抵抗力一般可由估算樁與其周圍土壤間之摩擦力而求得。對於黏性土壤，其與樁間之摩擦力係由其對樁之黏著力而來，大小則與黏土加於樁上之有效側壓力無多大關係。只要黏土對樁之黏著力估算正確，似乎所算得之樁拔起抵抗力應屬合理。樁在砂土層中時，由於砂土與樁間之摩擦力係由有效側壓力作用於樁上所產生，側壓力之大小直接影響其拔起抵抗力。因此，欲求得合理之樁拔起抵抗力，土壓力係數之決定成為最首要之條件。由於土壓力係數之現場測定不易，靠估計值所求得之拔起抵抗力自不可靠。欲求合理之拔起抵抗力，只有借重於基樁引拔試驗。本文主要在於討論砂土層中樁基之拉拔抗力，並分析三組現場基樁引拔試驗的結果，藉此探討周圍主要土層作用於樁上之側壓力係數經另一般估算所得之靜土土壓力係數及被動土壓力係數比較，可較了解樁在受拔時與其周圍砂土間之相互作用情形。
42. Cost
Consideration for Site Investigation
This paper discusses the basis for the development of reasonable unit rates
for site investigation work in Taiwan.
大地工程是綜合工程地質、土壤、岩石、地球物理以及水文等與工程有關之科學。任何一件土木工程不可或缺之基礎工程設計就是以大地工程調查之結果為依據，因此大地工程調查工作之成果將直接影響到該土木工程設計之安全與經濟。回顧國內近年來在十項建設及一般土木建築工程中，曾遭遇的許多困難問題均與大地工程有密切之關聯，因此大地工程調查工作之重要性逐漸廣被重視。大地工程調查工作與一般土木工程一樣，對業主而言，其要求乃是以最低之費用，在一定時間內，按照規定之調查方法得到令業主滿意之成果。但是大地工程與一般土木工程最大不同之處，就是大地工程具有多變與複雜之特質，因此導致調查成果之品質深受調查方法之選擇是否適當、工作執行是否確實以及研判是否正確之影響，因此「費用」不應是業主用來決定承包者的唯一因素。鑑於國內大部份之工程業主往往由於無法詳估合理之調查費用，而不得不以最低之費用來決定承包者。此種情況又常令業主擔心承包者之能力以及懷疑是否會偷工減料而影響工作成果品質。本文將對日本大地工程調查工作費用之考慮要項作一簡單之介紹與討論，與國內工程界人士共同研討並尋求編製合理調查費用之可行辦法，以為決定合理調查費用之依據，並祈我國大地工程調查工作能早日步上正軌。
43. Review
of Singapore Braddell Road Flyover "Turnkey" Project
After the completion of the 10 major construction projects in Taiwan, design
ability and construction skills of firms in the Republic of China has been
greatly improved. Ret-Ser Engineering Agency is not only becoming the leading
contractor in Taiwan but also being recognized internationally. In recent years
RSEA is becoming one of the major forces in ROC to export our construction
skill and techniques abroad. Singapore is a tropical island country with total
area of 618 sq.km. The geological condition has large variation. Subsoils near
the ground surface are mostly very soft clay which has many engineering problems.
The construction site of the Braddell Road Flyover of the Sanbawang Expressway
was covered with small ponds. To overcome the weak strength of the soft ground
and to keep the normal traffic flow of the existing Braddell Road were two
major problems during the flyover planning and designing phase. This project
was an international "Turnkey" project. Bid has to be low and design
has to be adequate to meet both engineering and architectural requirement.
Location reconnaissance site investigation, market study and all other prebid
work have to be done properly in order to win the contract. To win an international "Turnkey" project,
we have to have a strong design team and construction team working hand in
hand. Not only our engineering design skill but also construction techniques
have to be up to date. Only by gathering our best talents in the construction
field together, we can then win a position in the competitive world construction
market.
我國自十大建設完成，工程技術水準日益精進，不論在施工技術或設計實務能力隨著國家經濟的穩定發展同樣受到國際的重視。榮民工程事業處理處為配合政府輔導榮民就業的就定政策，也成為我國工程技術對外出的主力之一。新加坡為熱帶島國，幅員約618平方公里，人口約二百五十萬，地質變化相當複雜，靠近地表土層多為早期海中極軟弱粘土，工程上問題頗夕。山巴旺快速公路跨越布萊德路高架橋橋址池塘四處密佈，橋樑之規劃設計除須考慮其地盤軟弱之特性外，並須考慮既有布萊德路交通要道之通暢。本工程為一國際統包工程，不僅要達到其經濟的要求，並需兼顧與景觀的調和及美觀。舉凡現場勘查、工程地質探查或當地市場調查等先期工作皆須有通盤的了解以克竟全功。海外統包工程競標想與其他國際廠商抗衡，就須具備堅強的陣容，不斷提高術水準與技術人力的儲訓，充分發揮團隊精神，以爭取外人的認同的信賴，果能如此方能立於不敗之地。
44. Site
Investigation
For the design of any engineering constructed facilities, the responsible
engineer must play two important roles. Firstly, he must be able to "predict",
that is, to predict possible problems which may happen during the construction
and to predict the behavior or performance of the completed facility whether
it will meet the performance requirement of the project. Secondly, the engineer
must be capable of making proper judgment and decisions according to his prediction.
Unlike steel and concrete, soils and rocks are naturally occurring materials.
Their formations and properties can be extremely complex and variable. Characteristics
or behaviors of soils may vary with time, pressure and environment. Due to
these complex factors, the engineers in the geotechnical field faces an even
more challenging and difficult ask in making proper and "accurate" predictions.
In order to arrive at a solution, in other words, to make a good prediction,
one has to firstly acquire the necessary information and data. By combining
with appropriate theory and method, a solution may then be reached. Figure
1 illustrates the basic principles involved in making a prediction. It must
be emphasized at this point that "compatibility" is one of the most
important conditions in making a successful prediction. In other words, sophisticated
theories and methods should not be used unless there are adequate and reliable
data available as inputs. Many empirical relations were derived from results
of simple tests or observations. The use of results obtained from very sophisticated
tests in conjunction with these simple empirical relations may lead to completely
wrong "predictions". This compatibility is most important in the
field of geotechnical engineering. This paper will discuss the first item in
the prediction process, that is, information and data collection.
45. Diaphragm
Wall - Construction Quality Control and its Specifications
Quality control is the most important element in diaphragm wall construction.
The paper discusses the various factors which affect quality control including
capacity of machinery, excavation of guide trench, manufacture of reinforcement
cage, concreting, and control of stability of slurry.
挖掘槽溝並利用穩定液保持槽溝穩定再行水中灌鑄混凝土而成之地下連續壁、和其他形成之地下結構物不同，由於此類工程無論在挖掘，以至於完成混凝土之澆灌，均無法以肉眼直接判別其完整及精確度，且工程一旦完成，事後難以進行補救或補強，因而在施工中應如何訂定品質標準，並以適當可靠之方法評估其可信度，實宜於施工規範明確訂定，並合理的執行，在目前文獻中可見的規範較完整者如英國基樁專業人員聯會(Federation
of Piling Specilists,1973)所建議者頗為各國重視，美國於1981年(Millet & Perez，1981)所建議之標準，亦值得參考。連續壁施工之控制大致上可歸納為幾項重點:
1. 施工機具能力及其裝備。 2. 槽溝挖掘。 3. 鋼筋籠製作。 4. 混凝土澆灌。以及與槽溝挖掘之穩定性甚至與混凝土品質有密切關聯之 5. 穩定液控制，本文乃就此各要點提出檢討，以為施工監督者之參考。
46. Soil
Improvement by Compaction Sand Piles - Case Study
The paper describes a case study on the use of compaction sand piles for improving
sandy soils against potential earthquakes at the site of a steam power plant
in Suralaya Indonesia. Compaction sand piles of 50 cm diameter at 1.80 m spacing
were installed. The relative density of the sandy soil was increased from an
average of 46.5% to over 75%.
印尼政府於1978年規劃並委託加拿大 Monenco工程顧問公司於印尼爪哇島西部北端距雅加達約100公里之Suralaya處設計一座火力發電廠(圖一)，該火力發包廠預計發電量為2X400萬瓩(2x400
Megawatt)，包含主機六部。由於印尼亦位於環太平洋地震帶，該區又近火山活動區，設計單位建議應考成 0．3g 之地震加速度。經分析結果認為基礎地盤有液化可能，因此必需進行地質改良，經研判對於該區域之地層進行改良之可能方法為動力壓密法(Dynamic
Consolidation)或壓實砂樁法(Compaction Sand Pile)。由於印尼本地有經驗之地質改良廠商有限，同時也為顧及限制施工法而影響投標價格，該基地地質改良工程乃由設計公司定出改良效果規範後，以統包方式招標。投標廠商於投標時應指出其擬採用之改良方法、初步設計、施工控制預期成果及工程費用等。亞新工程顧問公司於
1979 年經印尼公司 P．T．Perkasa Andalas & Iron Steel公司之委託代為設計並擬具壓實砂樁改良施工計劃，經印尼電力公司評定採用，於1980年開工，至1982年完成全部基礎地盤之改良及基樁等基礎工程。本文就本案例之設計及改良施工結果提出報告．為工程界之參考。
47. High
Pressure Grouting
The paper presents a brief description on the basic principle, characteristics,
design and construction method of grouting with high pressure.
高壓噴射灌漿工法(High Pressure Jet Grouting)亦有稱為高壓噴流注入工法，噴射注入工法等，係屬於地盤改良灌漿工法中之一種，國內目前採用此工法者據筆者所知者有JSP、CCP、JOG等等，本工法發展之時間至今均有十數年，其開發之動機則係欲彌補一般灌漿工法所不易達成的目標，即常因土層之變異性及其中含有裂縫或空隙．致灌漿時藥劑易流向抵抗力較小之處。本工法係以高壓泵將水及空氣灌入並藉一特製的小口徑噴嘴使產生高壓噴射流以切削地層，切削的同時並將硬化劑
(主要為水泥) 注入，使與被切削的地層混合或取代之．以達成預定範圍內地層之強化或有止水效果之目的。根據柴琦光弘(1981)以上述技術於切削土壤時所需之噴射流吐出壓力大約在200至600kg/cm2，於切削岩盤時則需約2，000至6,000kg/cm2(如翡翠水庫採用之水刀、水鑽)，於切削卵石時則需達20,000kg/cm2以上，本文內容係限定於討論使用於土壤狀況。高壓噴射灌漿工法以似種類而言亦可分為三種:(1)柱狀噴流工法。(2)節間噴流工法。(3)翼狀噴流工法。本文主要討論為柱狀噴流工法，所謂"柱狀"，想像土是以鑽桿等速旋轉上升致同一平面上改良之範圍相等。惟實際上由於施工的控制、土層之變異性存在等原因，往往使其週邊成參差不齊之形狀，故在應用時需先具備此基本觀念。
48. Preloading
of Foundation Soil for Oil Storage Tanks
One 10,000 kl and seven 50,000 kl capacity oil tanks are to be constructed
in south-western part of Taiwan. A detail geotechnical investigation was carried
out. It was found out that the subsoils at the proposed tank site are mainly
of silty sand, clayey silt and silty clay with thin layers of fine sand. In
order to improve the bearing capacity and compressibility of the subsoils,
a preloading scheme was used along with field instrumentation monitoring for
evaluating the effectiveness of the soil improvement. Subsoil properties were
greatly improved resulting significant saving in construction cost by adopting
the preloading scheme.
七座直徑61公尺高度18.3公尺之五萬公秉油槽與一座直徑36.6公尺，高度12.2公尺之一萬公秉油槽，建立於臨海地區之沖積平原上，經詳盡的地基探查結果顯示，此沖積平原主要為沉泥質砂層及粘土質沉泥或泥質粘土夾細砂薄層組成。經採用預壓力方式之土質改良來減少油槽使用時之沉陷量，以達到油槽基礎穩定及槽體之安全。為了解並檢核預壓期間土質之變化，於預壓前裝設沉陷板與壓氣式水壓計觀測系統儀器，並於槽體完工試水試驗之前於槽體四周設置沉陷觀測點進行觀測，按兩階段之觀測結果顯示與原有分析結果極為接近，此亦證實若有詳盡的地基調查資料，並經合理的研判當可獲得經濟之油槽基礎設計。
49. Behavior
of Steel Shelled Piles at Singapore Marina Square
The difficulties and technical problems encountered during the installation
of 9,349 number of Raymond Step-Taper driven cast-in-situ piles in Marina Square,
Singapore are reviewed. The subsoil deposit at the site mainly consists of
layers of reclaimed sand, soft marine clays, loose to medium sand, stiff to
hard silty clay and very dense sand. Procedures of establishing set criteria
for driving the Raymond piles in these soil formation were established on the
basis of results of preliminary pile loading tests. The constructional control
was made flexible by adopting a set criterion combining terminal driving resistance
and aggregate number of blows required to drive a pile in order to accommodate
significant variation in the subsoil conditions at the site. The problem of
retapping of these driven piles due to heaving was evaluated.
50. Some
Aspects of the Construction Specifications of the Diaphragm Wall
The technique of constructing a concrete diaphragm wall using the slurry trench
method has been successfully adopted in many construction projects around the
world. Unlike other types of underground construction project, the entire structural
body is cast in slurry, where the quality and integrity of the structural element
can not be visually inspected until completion and exposure. Eventually, if
there is any defect, it will be extremely difficult, or even impossible, to
repair or reinforces. It is, therefore, important to have more thorough construction
specifications to improve the quality of construction and to ensure the structural
integrity and reliability of the diaphragm wall system. The specifications
recommended by FPS (1973) presented a fairly complete view of diaphragm wall
design and construction. Millet & Perez (1981) provide further critical
views on the tolerance of excavation and concrete placement, From the construction
point of view, the objectives of diaphragm wall specifications should give
a clear guide line on the following aspects. 1. excavation tolerance 2. Assembly
and placement of steel reinforcement cage 3. Tremie concrete process 4. Control
of slurry and stability of trench In the following paragraphs, the implementation
of these basic aspects will be examined.
51. Design
and Construction Considerations for Underpinning of Ai-Kuo Road Overpass
The proposed Taipei underground railway is crossing beneath the Ai-Kuo Road
Overpass bridge. The bridge pier (P10) is located inside the tunnel (Figure
1 and 2). The Taipei Railway Underground Project Office (TRUPO) has decided
to underpin the pier and transfer the pier load to the exterior retaining walls
of the tunnel. This paper discusses the design considerations and proposed
construction steps which incorporate various constrains of the project.
擬建之台北市區地下鐵路將經過愛國西路陸橋下方，而該橋之P10橋墩與隧道主體結構之衝突，地鐵工程處決定採用托底法，將P10橋墩之重量傳於隧道兩旁之連續壁擋土牆土。本文討論設計時所考慮之因素及設計之施工步驟。
52. Mountaineous
Roads - Some Important Design and Construction Considerations
Due to the inherent nature of complex topography, geology and environment,
design and construction of road system in mountainous regions demand special
considerations. The importance of geological assessment, hydrological study,
geotechnical investigation and environmental considerations are highlighted,
choice between technical consideration and economy are discussed, and brief
descriptions on factors to be considered in stability analyses and methods
for slope improvement and stabilization are presented. The paper emphasizes
the importance of adequate information collection, proper data interpretation
and sound engineering judgment.
53. Use
of Vertical Drains for Soil Improvement at Bridge Approaches
The subsoils underlying the approaches for the Braddell Road flyover in Singapore
include a surface layer of very soft peaty clay and marine clay varying in
thickness from 3 m to 11m. Embankments of 3.5 m and 4.0 m height were required
at the two approaches. Staged embankment construction and surcharge preloading
with vertical drains was employed to allow construction without foundation
shear failure and to reduce post-construction settlements. Prefabricated band
drains were installed at spacings of 1.1 m and 1.3 m. Instrumentation was installed
including piezometers, settlement plates and inclinometers. Stability during
construction was controlled by monitoring foundation pore pressures and lateral
deformations. Total settlements during construction and preloading were in
the order of 1.5 m, including 0.5 m of settlement due to undrained deformation
in the soft clay. Observed consolidation settlements were similar to those
predicted from conventional consolidation theory and laboratory test results.
Pore pressures did not dissipate as rapidly as expected from this theory and
the degree of consolidation indicated by pore pressures was less than that
indicated by settlements. Consolidation for 6 months under 10 per cent surcharge
successfully eliminated post-construction primary settlement beneath the north
embankment. Treatment for the south embankment was less successful because
the design preload duration was not achieved and because of less effective
drainage from the sand blanket.
54. Soil
Improvement for Foundation Treatment in Taiwan
Soil improvement techniques have been widely used to improve or to change
properties of soil deposits for the purpose of strength increase, settlement
control, seepage control, and reducing liquefaction potential under seismic
loadings. A major part of the useable land on the island of Taiwan consists
of alluvial deposits underlain by thick layers of soft silts and clays and
loose sands. These types of soils often require treatment or improvement before
they can be utilized to support constructed facilities. Otherwise, very costly
foundation systems may be necessary. This paper presents a general review of
the soil improvement techniques employed in Taiwan. Two case records are reported,
one uses prefabricated drains with preloading and the other case only utilized
the conventional preloading method.
55. Site
Investigation and In Situ Testing
On the occasion of the fiftieth anniversary of the International Society for
Soil Mechanics and Foundation Engineering, the Southeast Asian Geotechnical
Society is compiling a commemorative volume of articles describing the various
geotechnical activities and practices in the countries covered by the SEAGS.
This article describes some of the highlights of the site investigation practices
and types of in situ testings carried out for determination of the in situ
characteristics of soil deposits. Due to limitation of space, the article cannot
be comprehensive in its scope and coverages. Majority of the test results presented
in the paper are based on work carried out by the author's firm in various
countries in the region.
56. A
Study on Behaviour of Long H-Piles in Soft Ground
Many highrise buildings are supported by long H-piles. In cases where these
piles penetrate into a deep bearing layer underneath a thick layer of soft
clay, the verticality of these long piles and the behavior of pile under compression
loading are the important points for considerations in design. This paper describes
a study of all instrumental H-piles driven at a site to investigate the vertical
alignment after driving, the induced lateral movement of pile from driving
the adjacent piles, the deformation of pile, especially at the splicing joints
under loading test. Measurements of inclinometer tubes installed on the H-piles
can indicate that the vertical profiles of the H-piles can often exceed the
specified tolerances. Significant lateral movement of pile in the soft clay
layer may be induced by driving adjacent piles. The movement is related to
the distance of the adjacent pile driven. The vertical alignment of a pile
and its loading capacity can be affected by the strength of splicing joints.
A weak joint may cause joint failure or buckling of pile under loading. Splicing
joints stronger than normal should be designed for long piles. Plies with strong
splicing joints can pass pile loading tests to two times the design working
load, even with large lateral deflection after driving. Whilst bending of pile
appeals to be unavoidable, the importance of quality control and field supervision
for piling work cannot be overemphasized.
57. Ground
Improvement Works in South-East Asia
Soft ground deposits can be found In the subsoil profile of a number of cities
In the South-East Asian region. Bangkok, Jakarta, Penang and Singapore are
some of the major urban centers where soft ground conditions pose numerous
geotechnical problems. With the recent economic growth in this region, more
land is required for developments of high rise buildings and the associated
Infrastructure. Consequently, through various ground improvement techniques
usable land is reclaimed from the sea, swampy areas and relatively weak and
compressible ground. Work in these areas of ground improvement has only recently
taken on significant proportions in this region. In parallel with the present
upsurge in variety and scope of construction more often requiring specialist
services. Some methods such as soil nailing and geotextiles for soil reinforcement
have yet to attain the degrees of implementation and acceptance of ground improvement
techniques like deep compaction and the speeding up of consolidation, hence
the corresponding lack of publication on their application in projects. The
following report provides a general survey of some of the more significant
developments in the use of various methods of ground improvement In this region,
with reference to published material where available.
58. Soil
Improvement With Preloading and Vertical Drains
The use of prefabricated drains for accelerating the rate of consolidation
of a soft compressible silty clay at a reclamation project in Taipei is described.
The project site, covering an area of approximately 40 hectares, was an old
abandoned river channel underlain by a layer of sludge and 20 to 40m of soft
silt clay. The site was reclaimed for new town development by hydraulic fills.
Under the 2 to 4m of fill, the total settlement was estimated in the order
of over 60cm and will take more than 20 years. A detailed study was carried
out to evaluate the feasibility of reclamation. Soil improvement with vertical
prefabricated drains was adopted for accelerating the rate of consolidation
of the compressible soil stratum. A total of over 1.2 million linear meters
of drains was installed over the site. Monitoring records indicate that 6 to
10 months after installation of the drains, 75 to 95 per cent of the excess
pore pressures has dissipated and the degree of consolidation ranged between
74 to 95 per cent. The estimated residual settlements were less than 15cm which
met with the requirement for the new development.
59. Analysis
of Piezometer Data of Colluvial Slopes
台灣近年來開發山坡地日益增多，無論公共工程計劃，例如道路及水庫，或私人社區開發計劃，紛紛於山坡地展開。而鑒於台灣特殊之地質情況，許多區域地質上言之，多由砂岩、頁岩及砂頁岩互層構成，層面傾斜度甚大，且其上常覆蓋不透水之崩積土層
。此種地形及地質狀況常有不穩定之潛在可能。依近十年來台灣山坡地開發後的災害層出不窮狀況視之，山坡地之開發實有詳細調查及分析其穩定性之必要。於邊坡穩定分析中，地下水狀況為一項決定穩定性之重要參數。因水壓力不但一方面減低土壤之抗剪強度，同時亦增加滑動之上舉力，其值之高低直接影響邊坡之穩定程度。因此地下水之量測係邊坡穩定分析中必要之調查項目之一。然而又鑑於實際作業之困難，地下水位觀測甚難持續長期間，通常能持續觀測一雨季已屬難得。在此情形下常不易觀測到邊坡破壞時可能之最高地下水位。復由於現場調查作業中，水壓計數目有限，涵蓋面及淜蓋深度的不足，皆難以提供足夠之資料，以瞭解整體地下水文狀況。本文將根據台灣北部兩處山坡地所作之地下水觀測，分析崩積土山坡地之地下水狀況，地下水與降雨之關係，以及檢討估計地下水位升高之方法，以期獲得一較完整之現象。
60. Geotechnical
Considerations in the Planning and Design of Highways in Mountainous Terrain
Due to the inherent nature of complex topography, geology and environment,
design and construction of road system in mountainous regions demand special
considerations. The importance of geological assessment, hydrological study,
geotechnical investigation and environmental considerations are highlighted,
choice between technical consideration and economy is mentioned. Discussions
are focused on the importance of site investigation including hydrogeological
information,geological mapping, geotechnical analysis of cut slopes and fill
embankment, design of slopes, slope stabilization and remedial measures. Several
case records on design and betterment of roads and highways in Southeast Asian
countries are referred to in order to illustrate the various problems and approaches.
The paper emphasizes the importance of adequate information collection, proper
data interpretation and sound engineering judgment.
61. Stabilization
of a Legendary Hanging Cliff
Pyramid Hill in southern Taiwan has two monkey face like rocks on its western
slope. Local folks consider the rocks as a scenic landmark. There are also
legends about these rocks. During the construction of a highway passing under
these rocks, the slope below these rocks was excavated and replaced with a
retaining, wall. However, in a heavy storm, the retaining wall collapsed and
the Monkey Rocks slid almost two meters downslope causing fractures in the
rocks. A study was made to determine the feasibility of stabilizing the slope
and to preserve these natural scenic rocks. During the investigation stage:
boring, rock mapping and stereonets were utilized to provide maximum information
of the subsurface condition and state of rock fractures. Finally, rock anchors,
rock bolts, grouting, dental grouting and erosion protection, were selected
to stabilize the slope and the rocks. Since the stabilization was done, the
slope has weathered through many storms and no further movement was observed.
62. Consulting
Engineering Practice in the ROC
63. The
Piezocone Penetration Test
自從1974年的歐洲貫入試驗會議(European Symposium on Penetration Testing)和1975年ASCE土壤性質的現場試驗會議(Specialty
Conference on In-Situ Measuremeuts of Soil Properties)以來，大地工程界開始更注意到如何利用圓錐貫入試驗(Cone
Penetration Test, CPT)來探求土壤的性質。尤其現在的圓錐貫入試驗常具備了量測孔隙水壓的能力(例如電子式兼測水壓貫入錐(Piezocone,
Baligh.et al, 1981)，更可以幫助我們更精確的求到許多實驗室裏很難求到的土壤參數。同時，因為CPT可以取得連續的資料，所以比其他現場試驗工具更容易了解土層的變化；再加上CPT在其他基礎工程問題上直接的應用(例如樁基礎分析)，因而使得這個工具被視為兩種最有發展的現場試驗工具之一(Wroth,
1984)。本文目的，除了在介紹電子式兼測水壓貫入錐(以下簡稱水壓錐)本身的構造和使用時應該注意的事項以外，重點更在於如何利用水壓錐去鑑別土層及求得土壤參數。水壓錐也可以用來研究摩擦樁在黏土中的承載力，但因篇幅的限制，僅做簡略的介紹。至於許多有關水壓錐的基本理論(Baligh
1986 a, b)雖然非常重要，也都只有略去不談。
64. Design
of Caisson Retaining Wall for Slope Stabilization
邊坡穩定工程一般都以修坡之方式或擋土牆來處理，但在修坡之範圍受到限制或採用一般擋土牆在施工時，因基礎開挖而可能引起坍方時，可採用沉箱式之擋土結構來處理，此一方式並可配以預力岩錨以增加其穩定效果。沉箱式擋土結構一般而言其工程費較高，但在其他方法無法使用時，不失為可行方法之一。此方法對於必須垂直開挖之邊坡尤具效果，在香港地區使用，均能達成工程目的年來在國內亦已有施工之實例，謹予說明並提供參考。沉箱式擋土結構係以人工挖掘之方式建造(其直徑一般在1.0m~2.5m之間)，而後於沉箱內插入鋼筋籠後澆灌混凝土，使成為實心之鋼筋混凝土柱(見圖一)，並配置成列形成沉箱式擋土結構，沉箱內徑、間距依土壓大小而定，若在R.C擋土結構前方必須開挖時，沉箱間之空隙可打R.C版，使其成為完全連續之擋土牆，由於此類型擋土牆所受之土壓力通常較大，常須加設預力地錨(如圖二所示)以增加其穩定性。沉箱式擋土結構有下列之優點：
(1)可穩定較深之滑動面。 (2)施工所需之空間甚小。 (3)不需大型之施工機械，可在陡峭之邊坡施工。 (4)施工時不需大量開挖及回填，可免施工時因開挖而造成不穩定現象。依經驗利用沉箱處理坡地之方式，可概括分為四種等級(表一)，第一級為滑動深度小於10公尺之小型整治工程，第二級為滑動深度介於10公尺至20公尺之中型整治工程，第三級為滑動深度介於20公尺至30公尺之大型整治工程，第四級為滑動深度超過30公尺之超大型整治工程，基於工程材料強度與工程經濟之限制，深度小於30公尺之穩定處理方有其經濟上之效益，而大於30公尺之穩定處理方有其經濟上之效益，而大於30公尺之整治，由於工程所費不貲，除非基於特殊情況之限制，否則成本均甚高昂。
65. Disturbances
due to "Ideal" Tube Sampling
The "ideal sampling approach" (ISA) for elucidating, formulating,
and predicting minimum disturbance effects in deep tube samples of saturated
clays is proposed. The ISA relies on approximate solutions based on the strain
path method to incorporate tube penetration disturbances. Laboratory test results
on normally consolidated Boston blue clay indicate that the ISA provides more
realistic predictions than the existing perfect sampling approach and that
tube penetration disturbances are significant in "undisturbed" tube
samples of soft clays obtained by means of existing thin-walled sampling techniques.
66. Construction
Failures of Excavation in Soft Clay-Case Studies
Retaining structures used in excavations are usually designed based on semi-empirical
methods which may only pertain to some particular geological environment, this
paper describes two case histories in the newly developed area of Taipei City.
Experiences which apply to other parts of the city were found not applicable
in the very soft sensitive clays encountered. In both cases, the undrained
shear strength of the soil was over-estimated. Consequently, the original marginal
factors of safety used in the design of temporary structures were greatly reduced.
Field monitoring of the retaining system has helped to trace the causes of
failure and to arrive at remedial measures.
67. Behaviors
of Strut Braced Sheetpile Wall in Soft Ground Excavations
Four case records of sheetpile retained excavation in soft grounds in Taipei
and Singapore are presented. Behavior of sheetpile wall and associated ground
settlement at various stages of excavation and bracing are related to the construction
activities and found to be time dependent. Comparison of behaviour of sheetpile
wall was made with that of diaphragm wall at a same site.
68. Geotechnical
Engineering in Southeast Asia, Past, Present and Future
69. Preconsolidation
of Soft Bangkok Clay by Non-Displacement Sand Drains and Surcharge
The major geotechnical problem for the proposed development of an international
airport for Bangkok at Nong Ngu Hao, a possible site selected by the Department
of Aviation of the Government of Thailand, is the low strength and high compressibility
of the subsoils underlying the site. Study of the feasibility of soil improvement
scheme was one of the major item of work for the Master Plan Study, Design
and Construction Phasing of the proposed airport. In addition to theoretical
study and analyses, three test sections were designed, constructed and monitored
to evaluate the effectiveness of soil improvement. Non-displacement sand drains
of 26 cm diameter at different spacings were installed under the test sections
to approximately 14.5m in depth, i.e. to the underlying first stiff clay stratum.
Surcharge loading by fill was used at one of the test sections. Vacuum preloading
and groundwater lowering by pumping were used at the other two sections. The
test sections were well instrumented to monitor the vertical settlements, lateral
movements, changes in porewater pressures in the subsoils under the test area.
This paper reports the results obtained by using surcharge fill load with sand
drains for soil improvement. Comparisons of the actual soil behavior are made
with those from theoretical predictions as well as those obtained from test
sections studies without sand drains, it was found that the rate of settlement
of the Bangkok clay at Nong Ngu Hao can be effectively accelerated by the use
of non-displacement type sand drains.
70. Geotechnical
Engineering Mapping of the Taipei City
A major part of the Taipei City is underlain by sedimentary deposits with
the top 50 meters composed of loose sandy soils and soft clayey soils. Most
of the construction activities in the city have taken place in these subsoil
strata and are significantly affected by their geotechnical engineering characteristics.
The study, described in this paper, attempts to divide the basin area of the
Taipei City into zones according to the depositional characteristics, stratifications
and soil properties. Information on representative boring logs were collected
from major projects within the city. These projects include the N-S Intracity
Expressway, the proposed Mass Rapid Transit System, the Taipei Railway Underground
Project, the N-S Freeway, .and many highrise building projects. In total, information
on about seven hundred boring logs were compiled. Results of laboratory testings
on samples taken from these boreholes were also reviewed and compiled. On the
basis of their geological origin and sedimentary environment, the subsoils
in the Taipei Basin were divided into three major regions. They are: Tamshui
River Region, Hsintien River Region and Keelung River Region. From detailed
analysis of the composition, thickness of the various strata and engineering
properties of the soils, the three major regions were further divided into
seven zones. A series of geotechnical engineering maps were produced including
geological map, fence diagrams, isopachous maps of the various sublayers, isohyps
maps of the various sublayers, and a geotechnical zoning map.
71. Caisson
for Slpe Stabilization
Due to plate tectonic movement and rainy climate, the rocks in Taiwan are
usually fractured and highly weathered. Consequently, landslides have occurred
and covered the slope with layers of colluvial materials. Generally, the colluvium
is a heterogeneous geological material, often with various sizes of boulders
which limits the use of conventional bored or driven piles. Caissons have recently
been introduced to stabilize deep seated failure slopes in Taiwan. The earth
retaining structure, composed of closely spaced caisson, was constructed by
hand excavation and successively cast in place. This paper presents a comprehensive
site investigation of a landslide area in northern Taiwan, the mechanism of
slope progressive failure, the design of caissons to stabilize the slope, and
the construction of the retaining structure. Inclinometers were installed to
monitor the behavior of the landslide mass and to evaluate the performance
of the retaining structure.
72. Ground
Failures in Southeast Asian Countries
Ground failures occur in many different modes. Landslide is the most common
type of ground failure which may occur due to natural processes or man-made
activities or their combinations. With the exception of some large deltaic
plains, a large proportion of land area in Southeast Asia is hilly and mountainous.
Warm, wet climatic conditions, and sometimes augmented by seismic activities
are often responsible for landslide occurrence in the region. Due to the large
variation in the properties of residual deposits and the complex geological
conditions, many highways in mountainous terrain in Southeast Asian countries
were constructed without applying geotechnically satisfactory design procedures
but by judgement and precedents. Many slopes have failed and many others are
unstable. These resulted in large maintenance commitment, inconvenience, traffic
disruption and even safety. This paper describes a qualitative assessment approach
for categorizing slopes for hazard mitigation adopted for two highways crossing
mountainous terrains in Malaysia. The approach is extended and a quantitative
rating system is established for the Central Cross-Island highway in Taiwan.
73. Numerical
Analysis of Tunneling at Shallow Depth
在地表下之隧道開挖將造成隧道周圍土壤之應力解除，開挖周圍土壤因解壓而產生膨脹行為，並向隧道內移動，此現象最後會引起地表之沉陷，由地表位移量之大小及分佈可預測其對地上結構物的損害程度，此外由隧道之開挖，亦將改變周圍土壤的應力分佈，造成應力集中情形。隧道開挖引致之地表沉陷分析，一般是以經驗公式為常態分佈曲線(Normal
distribution curve)，對於隧道周圍之應力分析，則假設為在彈性的無限平板中之開挖(即平面應力觀念)，而以Kirsch solution分析之。然而真實的情況通常是在有限的土層內，接近地表處的隧道開挖，此時的沉陷分析和應力分佈並無適當的理論解可依循，而必須以經驗公式和數值分析法為之，本文以有限元素法模擬隧道開挖之情形，考慮其周圍土壤之應力和沉陷的大小及分佈，以探討一般沉陷公式及應力解在近地表隧道開挖時之適用性。
74. SPT-CPT
Correlations for Granular Soils
With the increasing use of the Cone Penetration Test (CPT), it would be of
significant value to establish a reliable correlation between the cone tip
resistance, qc, and the Standard Penetration Test (SPT) blow count, N-value.
Based on recent data obtained from sand deposits, a historical review on SPT-CPT
correlations is presented. For sands, the qc/N ratio decreases significantly
with increasing fine content. This paper suggests that the qc/N ratio can be
better correlated with fine content instead of the mean grain size for granular
soils. It is important for geotechnical engineers to be aware of the scatter
of the qc/N ratio caused by the inherent variability of the penetration tests.
The SPT N-value used to establish the local correlation should be corrected
by the energy level.
75. Method
for Studying the Ground Characteristics of Metropolitan Areas-Taking Boston
as an Example
台灣地區各大都市由於經濟繁榮、人口增加，許多大規模的坡地開發、衛生下水道、快速道路及大眾捷運系統等工程都在規劃興建之中。因此，倘能對各大都會區之地盤特性分別進行綜合性的研究，不僅能幫助一般工程之進行，更將有助於大規模工程之規劃以及都市發展之工作，以避免因缺乏對地層之了解所造成在設計、施工及使用階段的困擾。本文參考國外各大都市之經驗，並以美國波士頓地區為例，從資料收集、資料整理、地質研究、土壤與岩石工程性質探討、大規模現場試驗以及工程個案分析等方面來討論如何研究都會區地盤特性。在此特別強調本文的目的不在針對任何一個特定的都會區域提出建議，而僅就研究方向加以討論。
76. Experience
Gained in the Operation of Construction Management Technology in Private
Sector
由於政府自由化政策及民間資金之累積活絡，近年來私人企業投資興建之大型工程如旅館、購物中心及辦公大樓等成長迅速，且未來的發展潛力雄厚。現代營建管理之觀念及方法如何與追求利潤，反應敏銳，操作靈活之民間企業體系相結合以發揮其功能成為此一專業技術所面臨的新課題。本文將以實物運作的經驗就營建管理在民間企業體系中所採用的工作組織架構、發包策略、契約型態以及技術審核與施工監督之原則等加以報導，並針對其運作中面臨的問題加以探討，以期營建管理之操作能在此一新領域中循序發展並更趨成熟。
77. On
Removal of Organic Pollutants from Groundwater
地下水有機污染物之去除，用空氣提除法(針對VOC而言)，或用液相活性碳吸附法，均經證明甚為有效。若有機污染物除VOC外，尚有其他揮發性低或非揮發性者，則空氣提除法與液相活性碳吸附法兩者合併使用，常可獲得最佳之效益。在空氣污染物排放標準甚為嚴格之地區，由空氣提除設備所排出之廢氣，常須進一步加以淨化，最有效之廢氣淨化法為氣相活性碳吸附。
78. On
Short-Cut Solutions to Industrial Waste Problems
至目前為止，所有工業廢水之處理法，無論在學理上或操作上均屬可行，其所應考慮者，厥為成本與效率之問題，尤以成本問題最為重要。本省廢水處理之所以時至今日仍未見實施，最主要之原因乃是，任何方法之廢水處理，無論其為簡單或複雜，均必將增加廠方
之支出，而使其產品之成本因而提高，此當為各廠方之所以不樂於處理其廢水之主要關鍵所在。據此，吾人可知，任何足以降低廢水處理成本之方法或途徑，必將為廠方所樂於接受，因此當可減少廢水處理在執行上之困難與阻力，而使水污染防治之目標，得以早日實現。一般言之，影響廢水處理成本最重要之三項因素為，廢水量，廢水之污染濃度及河川自淨作用之能力。因此，吾人如欲降低廢水處理之成本，最有效之辦法不外，先設法由減少廢水量，降低廢水之污染濃度，及充分利用河川自淨作用之能力等三方面著手，否則廢水處理之成本，必將甚為龐大，實遠非在本省數目佔絕大多數之小規模工廠所能負擔者，如此將使日趨嚴重之水污問題久懸不決。且上述三項辦法簡便易行，如經各廠方全面實施後，再去考慮廢水處理廠之設立問題，應為處理廢水最經濟而有效之途徑。茲就此三項辦法評予討論於下列各節，以供各工業界之參考。
79. The
Application of the Expert System in Geotechnical Engineering
專家系統是人工智慧的領域中一項重要的發展。由於大地工程經常遇到不完整、不精確的問題，而決策過程中經驗與判斷更是扮演著關鍵性的角色，因此使得大地工程成為極適合發展專家系統的一個領域。本文介紹了國外一些已經發展完成的地工專家系統，並且討論了發展專家系統的工具，尤其強調發展應用於大地工程的專家系統，必須特別注意計算能力，資料庫的功能以及與繪圖程式的結合。最後，並提出幾個目前值得在國內發展專家系統的題目。
80. Site
Investigation
基地調查為基礎構造設計工作之重要步驟，本文之目的即針對建築技術規則建築構造編基礎構造設計規範(以下簡稱設計規範)中第三章「基地調查」加以說明討論，並將該章與建築技術規則(以下簡稱原技術規則)第二章第二節「地基調查」所規定之內容互比較，同時對於該章所未論及之問題加以補充說明。由於各基地地層性質不同，工程要求互異，本文更強調基地調查之工作除應符合設計規範之要求外，更應由專業之大地工程師編擬調查計畫，監督調查工作之執行，並撰寫調查報告之確保基地調查工作之品質，得以符合工程規劃、設計之要求。
81. Interpretation
of Instrumented Driven Steel Pipe Piles
This paper presents the results of a series of studies on the behavior of
driven close-ended steel pipe piles. Extensive field explorations and geotechnical
analyses have been carried out. Load tests were conducted, and strain gages
and tell-tales were installed on tested piles. The behavior of the instrumented
piles has been monitored for 14 months since pile driving. One emphasis of
this paper is upon the magnitude and distribution of residual stress after
pile driving and load testing. This paper also illustrates the setup of pile
capacities after driving, the difference in the ultimate skin friction of pile
under compression and under tension, and the development of negative skin friction
after pile load testing.
82. Predictions
of Capacities of Four Test Piles at Northwestern University
This paper presents the predictions of the axial load distributions of 4 test
piles at approximately 2 weeks, 1 month and 1 year after installation. Evaluations
of residual stress, pore pressure dissipation and other relevant factors were
considered in the predictions, but are not explicitly presented in this paper.
The shaft resistance in sand is predicted based on the LCPC method. A new approach,
the Kc method, is proposed in this paper to estimate the shaft resistance in
clay. Engineering judgment was exercised to take into account the installation
influences and mobilization effects.
83. Preconsolidation
of Soft Bangkok Clay by Vacuum Loading Combined with Non-Displacement Sand
Drains
There are many soil improvement techniques for decreasing post-construction
settlement of a site with soft clay deposit. In 1983, a geotechnical improvement
study program for the proposed Second Bangkok International Airport Project,
Thailand, was carried out. Soil Improvement techniques by means of non-displacement
sand drains with preloading by surcharge or vacuum or dewatering were tried
in test sections to investigate their effectiveness. The paper describes the
detailed method of using vacuum pressure. Due to air leakage through the top
soil layer, an airtight plastic sheet was needed to cover the test section
to achieve the required vacuum pressure. Full vacuum pressure could be applied
in the drains to consolidate the soil rapidly. It accelerated the settlement
rate of the test section similar to that with surcharge loading.
84. Environmental
Geotechnics in the Planning and Design of the Second N-S Freeway in Taiwan
It was decided that a second freeway be built in the northern region of Taiwan,
ROC, with a total length of 86.5 km. Moh and Associates, Inc. was responsible
for the planning and design of the southernmost section of 20.4 km, running
from Kuanhsi to Hsinchu. During the construction and after completion of the
existing freeway, a number of major problems, including landslides and serious
settlement, occurred, not only causing disruption of traffic movement, but
also having undesirable effects on the surrounding environment. Proper geotechnical
study and environmental control evaluation, therefore, became two of the most
important factors in the planning and design of the second freeway. This paper
describes the procedures and considerations that have gone into the planning
and design of the second freeway with respect to geotechnically related environmental
control.
85. Environmental
Impact In Geotechnical Engineering
The impact of the environment on civilization is the subject of the International
Decade for Natural Hazard Seduction (IDNHR). The IDNHR is sponsored by the
United Nations and begins in 1990. Its primary goal is to mitigate the consequences
of natural disasters such as earthquakes, tsunamis, landslides, etc. Concurrently,
the impact of civilization on the environment is the subject of the World Commission
on Environment and Development (WCED), also sponsored by the United Nations.
The WCED has concluded that the global economy and the global ecology are now
interwoven and interdependent. According to the WCED, disasters that appear
to be isolated, such as Bhopal and Chernobyl, are the result of mismanagement
of the global economy and ecology. The impact of humankind on the environment
is the primary subject of the present report. The current technical and legal
trends in America, Brazil, and Southeast Asia are summarized. It is concluded
that geotechnical engineers will continue to be very involved in developing
solutions to natural hazards. On the other hand, landfilling of municipal,
Industrial, and hazardous wastes is probably a temporary solution. In spite
of great advances in containment technology. In the future, these wastes will
likely be reduced, recycled, incinerated, or chemically stabilized. Consequently,
geotechnical engineers will have less and less to do with these wastes as mechanical
and chemical engineers develop alternative solutions.
86. Diaphragm
Wall Design Considerations for the Taipei Subway
Construction of the Taipei subway will involve deep excavations supported
by diaphragm walls and internal strutting. Ground deformations associated with
these excavations can have a significant effect on adjacent structures. The
data presented indicates that the strength of the material which forms the
passive zone in the excavation is a critical factor in controlling deformations.
Given the variability in material type and stratigraphy, the degree of swelling
which occurs during construction has a major influence on strength.
87. Professional
Practice in Southeast Asia
This report presents the current status and problems of geotechnical engineering
practice in five countries which belong to the Southeast Asian Geotechnical
Society. A survey questionnaire was sent to members of the local Associations
of Consulting Engineers and other known geotechnical consultants. Information
presented include profile and scope of practice, professional registration,
code of ethics, technical codes, professional liability, quality assurance,
business development, fee competition and major trends.
88. Engineering
Correlations for Soil Deposits in Taipei
This study aims at establishing empirical correlations for the soil deposits
in Taipei City. These correlations are valuable in the planning and preliminary
design stages. For cohesive soils, correlations between (1) virgin compression
index and natural water content, (2) virgin compression index and initial void
ratio, (3) coefficient of consolidation and liquid limit, and (4) angle of
shearing resistance and plasticity index are proposed. Profiles of over consolidation
ratio (OCR) as well as strength ratio are presented. Relationships between
the coefficient of earth pressure at rest and the angle of shearing resistance
and the plasticity index have also been carefully studied. For cohesionless
soils, correlations between (1) permeability and effective particle size, and
(2) angle of shearing resistance and standard penetration test (SPT) N-value
are presented. Due to inherent variations in the Taipei soil deposits, there
are practical limitations and the correlations presented in the paper should
be used with great care.
本研究之目的在利用相關性分析建立臺北市土層工程參數之經驗公式，而此相關性分析之結果，將極有助於日後工程建設之規劃及初步設計。對於凝聚性土層，本文提出下列各項參數之關係式:(1)原始壓縮指數與自然含水量，(2)原始壓縮指數與初始孔隙比，(3)壓密係數與液性限度，及(4)有效抗剪角與塑性指數。本項研究亦分別提出過壓密比及強度比對深度的剖面圖，並對靜止土壓力係數與有效抗剪角及塑性指數之關係加以研究。對於非凝聚性土壤，則提出(1)透水性與有效粒徑，及(2)有效抗剪角與
SPT N值之關係式。由於臺北市土層原有的變異性，因此這些關係式有其實際上之限制，而在使用時仍需審慎研判。
89. Relationship
Between Undrained Shear Strength and Overconsolidation Ratio of Taipei Silt
The purpose of this paper is to use isotropically consolidated triaxial compression
test results to verify the normalized behavior of the cohesive soils of the
Sungshan Formation in the Taipei Basin. Testing procedures which overcomes
the difficulties due to disturbance effects are proposed. Following the SHANSEP
approach, the relationship between the undrained shear strength ratio and over-consolidation
ratio is established. The authors propose methods which can be used to obtain
reliable values for undrained shear strength properties needed in project design.
本文的目的在以均向壓密三軸剪力試驗證實臺北盆地松山層凝聚性土壤的常化行為，建議克服土樣擾動影響的試驗方法，並以SHANSEP的觀念建立強度與過壓密比之關係；於工程設計時，可依工程之特性及其重要程度，根據本文所建議之方法，即可求得可靠之不排水剪力強度。
90. Trial
Embankment With Stage Loading and Vertical Drains
This paper presents the basic design philosophy and performance evaluation
of a trial embankment on 16-18m thick soft clay deposit with stage loading
and vertical drains. The project is one of the 10 trial embankments with different
soil improvement methods carried out under the sponsorship of the Malaysian
Highway Authority. Due to practical constraints in carrying out the construction,
the embankment was built to only 4.75m high instead of the intended 9.0m. Although
definite conclusions regarding the scheme could not be drawn yet at this stage
due to the short time available for monitoring, field settlement data do indicate
that the vertical drains accelerated the rate of settlement and stage loading
could be a feasible way in controlling stability of fills on soft ground.
91. The
Distribution of the Gravel Layer in the Taipei Basin
This paper is aimed at studying the distribution of the gravel layer in the
various areas of the Taipei Basin. The main focus is the gravel layer of the
Chingmei Formation, which is of utmost engineering concern because it is always
considered as the bearing stratum of deep foundations in Taipei. Recent drilling
records indicate that the distribution and depth of the gravel layer in Taipei
varies significantly according to the geological history of the Taipei Basin
and the sedimentation conditions of the three major rivers flowing into the
Basin. The general conditions of the gravel layer in Taipei Basin are discussed,
along with the distribution of the gravel layer in such areas as Hsintien-Kungkuan,
east area of Taipei City, Yungho City and Nankang District along Keelung River.
本文旨在研究臺北盆地內不同地區礫石層分佈之狀況，討論之重點為於臺北盆地中被視為良好深基礎承載層之景美層礫石。最近之鑽孔資料指出，臺北盆地中礫石層分佈犬狀況及深度受到臺北盆地地史演變及三條主要河川沉積特性之影響而有相當大的差異。本文並針對新店至公館一帶、臺北市東區、永和市區及南港區沿基隆河一帶等幾處地區礫石層分佈之情形，根據最近鑽孔之資料加以研判並分別說明。
92. The
Application of Cam-Clay Model in Interpreting the Results of Triaxial K0
Consolidation Tests
An automated triaxial testing device was used in this study to investigate
the K0 value of Taipei silty clay. It was found that under different initial
stress conditions, the resulting effective stress paths would assume different
shapes which causes difficulty in interpreting the test results. Numerical
analyses based upon the modified Cam-Clay model were subsequently conducted
to gain an insight look regarding the characteristics of the K0 consolidation
tests. The numerical results showed that the modified Cam-day model is suitable
for interpreting the test results. It is also concluded that the accuracy of
K0 value derived from K0 consolidation test depends very much on the capability
of the automated cell in limiting the lateral deformation. A guideline for
determining the K0 values for Taipei silty clay via automated laboratory testing
procedures is also provided.
93. Planning
of Second N-S Freeway (Kuanhsi-Hsinchu Section) in Taiwan
In order to relieve the traffic congestion on the existing Chung Shan Freeway
it was decided by the government in 1985 that a second freeway be built in
the northern region of Taiwan, ROC, with a total length of 86.5 km. Moh and
Associates, Inc. was responsible for the planning and design of the southernmost
section with section length of 20.4 km, running from Kuanhsi to Hsinchu. The
route corridor of the section crosses undulating terrain with complex geological
conditions. The topographical and geological conditions are two of the major
factors influencing the planning work of the new freeway. This paper describes
the procedures and considerations that have gone into the planning and design
of this section with respect to the major features, such as route selection,
slope stabilization and its protection, structure types, and landscaping-related
highway engineering. In addition, modern design concepts and new construction
methods were introduced with care, including the use of a computer-aided design
and drafting (CADD) program system.
94. Shear
Strength Properties of Some Malaysian Residual Soils
High cuts in granitic residual soil deposits for construction of new highways
are common in Peninsula Malaysia where about a third of the land area is underlain
by granitic and other non-volcanic igneous rock formations. Frequent failures
of these slopes during raining seasons had become an increasing problem. A
good understanding of the behavior of these granitic soils is important to
the geotechnical engineers in carrying out analyses and design of the slopes.
A detailed geotechnical study was carried out in 47 failed cut slopes along
the existing Kuala Lumpur-Karak Highway. Four different types of shear strength
tests were performed on undisturbed samples taken from these slopes. They include
conventional single-stage and multi-stage CIU tests, direct shear tests, and
a non-conventional triaxial test in which an anisotropically consolidated specimen
was brought to failure by increasing the pore water pressure. Shear strength
parameters obtained from these four different types of tests were compared
and evaluated. Their applicability in the slope design was studied through
back analyses of failed slopes. It was found that, the pore water pressure
controlled triaxial tests gave higher value of the angles of shearing resistance
than those obtained from both the multi-stage and single-stage CIU tests. The
multi-stage CIU tests gave higher effective cohesion intercept than those obtained
from the other tests. Back analyses of the failed slope using the strength
parameters obtained from the different shear tests showed that the safety factors
estimated for the observed sliding surfaces were less than unity in most cases.
The strength parameters from pore water pressure controlled tests appeared
to give a safety factor nearest to unity.
95. The
Study of Fly Ash Stabilization on Lateritic Soil in Taiwan
A laboratory experimental Investigation was carried out to study the effects
of the addition of fly ash on the physical and chemical properties of lateritic
soils In Taiwan. This paper describes the design of the experiment, where type
F fly ash and lime were applied to two kinds of soils. Harvard miniature compaction
tests, unconfined compression tests, swell tests, pH tests and Atterberg limits
tests were performed on the fly ash treated soil samples. Test results showed
that the physical and chemical properties of treated soils had been significantly
affected by fly ash-lime stabilization, including plastic indices, swelling
potential and strength characteristics. Exception may occurs on the low quantity
of fly ash used with soils. Using pH method to define the "Fly Ash Modification
Optimum" (FAMO), as the unit for amount of fly ash adds in soil, is the
effective method to approach the purpose of soil stabilization.
96. Long
Term Geotechnical Studies at the Hsin-Ta Power Plant Site
The Hsin-Ta Fossil Power Plant is constructed on a piece of reclaimed land
in 1978. All the major structures are supported by piles. Due to the presence
of deep seated compressible soil strata, the entire site including the piled
structures has been progressively settling. In 1982, the settlement rate has
accelerated because of increase of pumping of groundwater for fishery farms
in areas adjacent to the Plant. In 1987, instrumented test piles were installed
to verify the development of negative skin friction due to subsidence. This
Paper describes the geotechnical conditions of the site, foundation considerations
in the early stage, settlements of the existing structures, long term groundwater
monitoring results and subsidence of the area. Discussions also cover the negative
skin friction monitoring of the test piles.
97. Properties & Origins
of Singapore Boulder Bed
Extensive areas of central Singapore are underlain by a deposit of stiff clay
containing often massive guartzite boulders. This the so-called "boulder
bed" lies on a flat table formed by a downthrust about 20 million years
ago. The deposit appears colluvial, and data from the construction of the Singapore
Mass Rapid Transit System, has confirmed that rock with a similar composition
and strength occurs in-situ near the area of the deposit. Deposition of this
boulder bed could have been a result of massive mudflow occurred about one
million years ago. MRT Construction also allowed the bulk shear strength of
the boulder clay to be back-analyzed from records of excavation, anchors, piles
and tunnels.
98. A
Comparison of Cut-and-Cover with Bored Tunnels Through Soft Clay in Singapore
The construction of the Singapore Mass Transit System involved 16.8 km of
twin running tunnels formed by both bored and cut-and-cover techniques. The
selection of a particular method required careful consideration of a large
number of variables. Soft clay deposits are widespread and one of the most
difficult construction strata in Singapore. Two sections of tunnel built in
this medium are used to illustrate the selection procedure. The reasons for
accepting a contractor's alternative bored tunnel proposal using Earth Pressure
balance shields are given and a comparison of the settlement effects of the
bored tunnels and adjoining cut-and-cover stations presented. In a section
in undeveloped reclaimed land the cut-and-cover method was used, and here settlement
and negative skin friction were the principal design considerations. An economic
pile design was developed with the aid of instrumented test piles. The excavation,
carried out under water, is briefly described and the potential advantages
of this method are noted.
99. Settlements
During the Underground Construction of the Singapore MRT
The two major elements of the settlement resulting from bored tunnelling or
deep excavation are the immediate (ground loss) component and the consolidation
component. Based on experience gained in soft clays in Singapore it is possible
to distinguish three forms of consolidation settlement due to bored tunnelling.
Examples of the form and magnitude of the resulting settlement troughs are
given. Ground loss settlements due to bored tunnelling are illustrated by a
comparison between the results of two adjoining drives one using earth pressure
balance shields and the other using open face shields with compressed air.
The behaviour of buildings founded on rafts or short piles is contrasted with
those fully piled. Some surprising conclusions are drawn both of the respective
merits of the bored tunnelling methods described and also the effect on buildings
adjacent to the MRT construction.
100. Geotechnical
Characteristics of Soils in the Taipei Basin
This paper summarizes some geotechnical data gathered from various projects
carried out in the Taipei Basin. The purpose is to highlight geotechnical problems
and to reflect areas of future studies. The general subsoil profile and zoning
of subsoils are presented. Distribution of gravel and gas emission problem
are reported. Preliminary correlations for the subsoils properties are established.
Discussions are focused on the major geotechnical problems in the Basin; which
covers groundwater drawdown and recovery, ground subsidence and possibility
of soil liquefaction. Field monitoring data were compiled to indicate the behaviors
of deep excavation including the penetration depth of retaining wall, bottom
heave, wall deflection and ground settlement. Comparisons of piles resting
on the gravel layer with clean base and soft slime base are made to show the
significance of installation process of piles.
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