Unconventional concepts for dykes and dams on soft clay foundation

1984 ◽  
Vol 21 (3) ◽  
pp. 581-586
Author(s):  
O. Eide ◽  
S. Lacasse ◽  
B. Kjærnsli ◽  
P. S. Hafskjold
Keyword(s):  
Key Words ◽  
Soft Clay ◽  
Earth Pressure ◽  
Soil Improvement ◽  
Construction Time ◽  
Sloping Ground ◽  
Vertical Drains ◽  
Clay Deposit ◽  
Clay Deposits ◽  
Improvement Measures

As an alternative to a stage-construction embankment dyke equipped with vertical drains, two buttress-type concrete dams are proposed for deep, soft clay deposits where the building of embankment dykes would involve serious difficulties and sizable expenditures. These concepts avoid the loading of the soft clay deposit with high embankments and thus reduce problems of stability and settlement. High embankment dykes may not be feasible in the case of sloping ground, even gently so, because of the lack of stability in a flake-type sliding. The advantages of the proposed concept include the absence of soil improvement measures, shorter construction time, and reduced settlements. Specific drawbacks relate to the lack of experience with buttress-type dams on soft clay foundations. Key words: dam, clay, concrete, earth pressure, embankment, pile.

The coefficient of earth pressure at rest

1993 ◽  
Vol 30 (4) ◽  
pp. 647-666 ◽  
Author(s):  
G. Mesri ◽  
T.M. Hayat
Keyword(s):  
Soft Clay ◽  
Earth Pressure ◽  
Stress Path ◽  
Vertical Stress ◽  
Deformation Condition ◽  
Granular Soils ◽  
Empirical Equations ◽  
Angle Of Internal Friction ◽  
Secondary Compression ◽  
Clay Deposits

Laboratory experiments on undisturbed specimens of a large number of soft clay deposits, as well as previous measurements on clays and granular soils, were used to examine and explain the magnitude and behavior of the coefficient of earth pressure at rest, K0: (i) after sedimentation – primary consolidation, (ii) during secondary-compression aging, (iii) after active or passive preshearing away from the laterally constrained condition, (iv) during a decrease in effective vertical stress, and (v) during an increase in effective vertical stress in the recompression or compression range, in terms of [Formula: see text], the slope of the effective horizontal [Formula: see text] versus effective vertical[Formula: see text] stress path. The behavior of K0 is explained using the concept of mobilized angle of friction in laterally constrained deformation condition. The Jaky equation provides, in terms of the angle of internal friction, a good estimate of K0 of sedimented, normally consolidated young clays and granular soils, as well as of [Formula: see text] of presheared clays and sands, and of densified granular soils that are subjected to laterally constrained compression from [Formula: see text]. Empirical equations provide reasonable estimates of K0 for clays and granular soils after secondary-compression aging, after preconsolidation by unloading, and for soft clay deposits that display a preconsolidation pressure [Formula: see text] greater than in situ effective vertical stress [Formula: see text]. Proposed empirical equations and methods successfully predict K0 of presheared clays. Key words: coefficient of earth pressure at rest, soft clays, granular soils, presheared soils, sampling and laboratory testing.

scholarly journals Large scaled field tests on soft Bangkok clay

2021 ◽  
Vol 44 (4) ◽  
pp. 1-23
Author(s):  
Arumugam Balasubramaniam
Keyword(s):  
Ground Improvement ◽  
Large Diameter ◽  
Soft Clay ◽  
Field Tests ◽  
Field Measurements ◽  
Deformation Analysis ◽  
Residual Soil ◽  
Kuala Lumpur ◽  
Vertical Drains ◽  
Clay Deposits

In this lecture the interpretations of fully instrumented tests embankments and their role in the development of appropriate ground improvement techniques for highways, motorways and airfields on soft clay deposits is illustrated through well documented case studies in Bangkok, Thailand and Muar Flat Site in Kuala Lumpur. For the Bangkok Plain and with sand backfills the performance of embankments with different schemes of vertical drains was evaluated over a period of 25 years. Aspects such as recharging effects due to the drains, inadequate measures in maintaining vacuum during vacuum applications and possible hydraulic connections with large diameter drains are discussed. For the Muar test embankments, the role of fill strength in residual soil embankment and the field deformation analysis in separating consolidation settlement from immediate settlement and creep settlements is presented. Novel interpretations of settlement from pore pressure dissipations, secondary settlement from field measurements and decay of lateral deformation rate with time were also made.

A case record of electroosmotic consolidation of soft clay with improved soil–electrode contact

2004 ◽  
Vol 41 (6) ◽  
pp. 1038-1053 ◽  
Author(s):  
Fabien Burnotte ◽  
Guy Lefebvre ◽  
Gilles Grondin
Keyword(s):  
Chemical Treatment ◽  
Soft Clay ◽  
Soil Improvement ◽  
Field Application ◽  
Large Field ◽  
Published Data ◽  
Power Losses ◽  
Case Record ◽  
Clay Deposits ◽  
Electrode Contact

Electroosmotic (e.o.) consolidation of clays has been known in geotechnical engineering for many decades but is in fact seldom used. The analysis of published data from case records indicates that the power losses at the soil–electrode contact constitute a major problem for the field application of e.o. consolidation. A laboratory study, where field conditions were reproduced, has demonstrated the efficiency of a chemical treatment at the electrodes to enhance potential transfer to soil. The chemical treatment was evaluated in a large field demonstration test where over 700 m3 of clay was consolidated by electroosmosis. The paper describes the site, the field setup, and the results and analysis of the monitoring during the 48 days of the e.o. treatment. The results of the post-treatment geotechnical investigation after 12% of clay compression due to electroosmotic consolidation are also presented and discussed. These results confirm that soft clay deposits can be successfully treated by e.o. consolidation, at a competitive cost compared with other alternatives, when power losses at the soil–electrode contact are controlled.Key words: case record, electroosmosis, soft clays, consolidation, soil improvement.

A precompression method of soft ground improvement using dewatering

1991 ◽  
Vol 7 (1) ◽  
pp. 651-658
Author(s):  
H. Kotera ◽  
T. Sakemi ◽  
T. Matsui
Keyword(s):  
Water Pressure ◽  
Ground Improvement ◽  
Soft Clay ◽  
Soil Improvement ◽  
Tokyo Bay ◽  
Soft Ground ◽  
Improvement Project ◽  
Vertical Drains ◽  
Clay Ground ◽  
Soft Ground Improvement

AbstractThe background and geology of the Tokyo Bay area of Japan, and recent soil improvement methods used in Japan are described. The vertical drain method has frequently been used to improve thick quarternary deposits in this area. This paper describes a case history of a dewatering method in combination with the vertical drains and preloading in a major soft ground improvement project in the Urayasu area of the Tokyo Bay. The dewatering method is a vacuum consolidation method, which is tentatively applied to the soft clay ground.In the combined dewatering method, the waterhead in a vertical sand drain is lowered by pumping the water from a sand layer within or below a soft clayey layer using deep wells. The dewatering applies negative water pressure to the soft clayey layer, promoting its consolidation.The authors confirm the consolidation effect of the dewatering and establish the applicability of the combined dewatering method to the soft clay ground.It is concluded that the dewatering method described significantly increases the shear strength and the consolidation yield stress of the soft clayey layer.

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