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.

Back-calculation of consolidation parameters from field measurements at a reclamation site

2001 ◽  
Vol 38 (4) ◽  
pp. 755-769 ◽  
Author(s):  
Lai Fa Cao ◽  
Ming-Fang Chang ◽  
Cee Ing Teh ◽  
Yung Mook Na
Keyword(s):  
Pore Pressure ◽  
Land Reclamation ◽  
Ground Improvement ◽  
Field Measurements ◽  
Coefficient Of Consolidation ◽  
Vertical Drains ◽  
Undisturbed Samples ◽  
Back Calculation ◽  
Reclamation Project ◽  
Consolidation Parameters

A pilot test was carried out at a land reclamation project site to study the effect of vertical drains on the rate of consolidation of a marine clay deposit in Singapore. Theoretical and numerical analyses were conducted to interpret the field measurements of pore pressure and settlement, and consolidation parameters were back-calculated. The back-calculated preconsolidation pressure is similar to that obtained from the laboratory consolidation test on undisturbed samples, but the field-deduced compression index is generally larger than that measured in the laboratory. The coefficient of consolidation back-calculated from the settlement measurement is larger than that from the pore-pressure measurement. The coefficient of consolidation for horizontal flow obtained from the Rowe cell test, which is comparable to that back-calculated from the field settlement measurement, is recommended for the preliminary design of vertical drains without the need of considering the smear effect.Key words: clays, consolidation, ground improvement, numerical modelling and analysis, permeability, vertical drains.

Top-down Excavation of a Metro Station in Soft Clay

2011 ◽  
Vol 368-373 ◽  
pp. 2866-2869
Author(s):  
Ye Lu ◽  
Yong Tan
Keyword(s):  
Soft Clay ◽  
Field Measurements ◽  
Top Down ◽  
Metro Station ◽  
Vertical Movements ◽  
Steel Columns ◽  
Axial Forces ◽  
Clay Deposits ◽  
Diaphragm Walls

This study examines the performance of a deep metro excavation constructed by top-down technique in Shanghai clay deposits. The monitoring items included deflections of diaphragm walls, vertical movements of steel columns, and axial forces of the struts. Based on analysis of the field measurements, some interesting findings were obtained, which will be useful for both practitioners and researchers.

Analytical solution for radial consolidation considering soil structure characteristics

2015 ◽  
Vol 52 (7) ◽  
pp. 947-960 ◽  
Author(s):  
Cholachat Rujikiatkamjorn ◽  
Buddhima Indraratna
Keyword(s):  
Ground Improvement ◽  
Soft Soil ◽  
Soft Clay ◽  
Excess Pore Pressure ◽  
Vertical Drains ◽  
South Wales ◽  
Surcharge Load ◽  
Speed Up ◽  
Soil Compressibility ◽  
Conventional Models

A system of surcharge load combined with vertical drains to speed up consolidation of soft soil by reducing the drainage path is one of the most efficient and economical ground improvement techniques. In the field, conventional theories including smear zone have been commonly employed to predict the radial consolidation behaviour induced by vertical drains in soft clay. One of the key parameters in conventional analysis is the use of mean coefficient of volume compressibility and soil permeability, which are often assumed to be constant. The effect of drain installation on the soil compressibility of the in situ clay structure is often ignored. Laboratory testing has shown that the soil compressibility and permeability can vary nonlinearly over a considerable range of applied surcharge pressure, and both these properties can be affected during the drain installation. This study presents a mathematical model of radial consolidation via vertical drains incorporating the variations of soil compressibility and permeability as well as highlighting the effects of drain installation on those parameters. The main differences between the proposed and conventional models are elucidated, in terms of stress history and preloading (surcharge) pressure. The effects of preconsolidation pressure and the magnitude of applied preloading are examined through the dissipation of average excess pore pressure and associated settlement. Supported by experimental observations, the proposed theory is validated with field data of a selected case study in the town of Ballina, New South Wales, Australia.

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.

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.

scholarly journals Prefabricated vertical drains (PVDs) in soft Bangkok clay: a case study of the new Bangkok International Airport project

2002 ◽  
Vol 39 (2) ◽  
pp. 304-315 ◽  
Author(s):  
Dennes T Bergado ◽  
A S Balasubramaniam ◽  
R Jonathan Fannin ◽  
Robert D Holtz
Keyword(s):  
Soft Clay ◽  
Field Measurements ◽  
Full Scale ◽  
Maximum Height ◽  
Vertical Movements ◽  
Prefabricated Vertical Drains ◽  
Vertical Drains ◽  
International Airport ◽  
Prefabricated Vertical Drain ◽  
Test Embankment

This paper presents the performance of a full-scale test embankment constructed on soft Bangkok clay with prefabricated vertical drains (PVDs) at the site of the new Bangkok International Airport in Thailand. The embankment was square in plan with a maximum height of 4.2 m, 3H:1V side slopes, and base dimensions of 40 m by 40 m. The piezometric level with depth is characterized by negative drawdown starting at around 8-10 m depth caused by excessive withdrawal of groundwater. Instrumentation was provided to monitor both horizontal and vertical movements of the test embankment. The measured increases in undrained shear strengths with depth are in agreement with the values calculated from the SHANSEP technique. The secondary compression ratio, Cα, was 0.018, or within the normal values for marine clays. The coefficient of horizontal consolidation measured in the field, Ch(field), was higher for soil at 4 and 10 m depths than for the weakest soil at 6 m depth. The back-calculated Ch(field) values range from 3 to 8 m2/year, and the ratio of Ch(field) to Ch(lab) ranges from 4 to 5, where Ch(lab) is the coefficient of horizontal consolidation measured in the laboratory. The degree of consolidation estimated from the pore-pressure dissipation measurements agreed with those obtained from settlement measurements. The water-content reductions from field measurements were also in good agreement with the values computed from the consolidation settlements. The full-scale study confirmed that the magnitudes of consolidation settlements increased with the corresponding decrease of PVD spacing at a particular time period. Lastly, the results of the full-scale study have proven the effectiveness of PVDs for the improvement of soft Bangkok clay.Key words: soft clay, consolidation, prefabricated vertical drain, preloading, test embankment.

Numerical modeling of vertical drains with smear and well resistance installed in soft clay

2000 ◽  
Vol 37 (1) ◽  
pp. 132-145 ◽  
Author(s):  
B Indraratna ◽  
I W Redana
Keyword(s):  
Pore Water Pressure ◽  
Water Pressure ◽  
Soft Clay ◽  
Field Measurements ◽  
Prefabricated Vertical Drains ◽  
Vertical Drains ◽  
Modified Cam Clay ◽  
Lateral Displacements ◽  
Strain Model ◽  
Cam Clay

This study describes the behavior of embankments stabilized with prefabricated vertical drains installed in soft clay foundations, based on several fully instrumented case histories selected from Thailand and Malaysia. A multidrain analysis is conducted based on an equivalent, plane strain model developed by the authors. The deformation of soft clay beneath an embankment (i.e., along and away from the centerline) is predicted and compared with the available field measurements. The effects of both smear and well resistance are incorporated in the analytical formulation, which is used in conjunction with the modified Cam-clay theory. It is demonstrated that the installation of vertical drains significantly increases the rate of settlement, improves the dissipation of pore-water pressure, and decreases the lateral deformation of the soft clay foundation. To obtain better predictions, especially of pore pressures and lateral displacements, the equivalent discharge capacity of the drains needs to be modeled appropriately. The inclusion of the effects of smear and well resistance in the analysis of vertical drains improves the accuracy of predictions significantly, in comparison with the field measurements.Key words: clay, consolidation, embankment, finite element method, settlement, smear zone, vertical drain.

scholarly journals Underwater Holographic Sensor for Plankton Studies In Situ Including Accompanying Measurements

Sensors ◽  
2021 ◽  
Vol 21 (14) ◽  
pp. 4863
Author(s):  
Victor Dyomin ◽  
Alexandra Davydova ◽  
Igor Polovtsev ◽  
Alexey Olshukov ◽  
Nikolay Kirillov ◽  
...  
Keyword(s):  
World Ocean ◽  
Field Tests ◽  
Field Measurements ◽  
Measuring Systems ◽  
Water Turbidity ◽  
Background Data ◽  
Average Size ◽  
Size Dispersion

The paper presents an underwater holographic sensor to study marine particles—a miniDHC digital holographic camera, which may be used as part of a hydrobiological probe for accompanying (background) measurements. The results of field measurements of plankton are given and interpreted, their verification is performed. Errors of measurements and classification of plankton particles are estimated. MiniDHC allows measurement of the following set of background data, which is confirmed by field tests: plankton concentration, average size and size dispersion of individuals, particle size distribution, including on major taxa, as well as water turbidity and suspension statistics. Version of constructing measuring systems based on modern carriers of operational oceanography for the purpose of ecological diagnostics of the world ocean using autochthonous plankton are discussed. The results of field measurements of plankton using miniDHC as part of a hydrobiological probe are presented and interpreted, and their verification is carried out. The results of comparing the data on the concentration of individual taxa obtained using miniDHC with the data obtained by the traditional method using plankton catching with a net showed a difference of no more than 23%. The article also contains recommendations for expanding the potential of miniDHC, its purpose indicators, and improving metrological characteristics.

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