Deformability and consolidation characteristics of soft Bangkok clay using screw plate tests

1990 ◽  
Vol 27 (5) ◽  
pp. 531-545 ◽  
Author(s):  
D. T. Bergado ◽  
K. C. Chong ◽  
P. A. M. Daria ◽  
M. C. Alfaro
Keyword(s):  
Graphical Method ◽  
Soft Clay ◽  
Stress Path ◽  
Soil Parameters ◽  
Test Results ◽  
Coefficient Of Consolidation ◽  
Plate Test ◽  
Settlement Time ◽  
Oedometer Tests ◽  
Test Embankment

This study centred on the performance of the screw plate test (SPLT) to determine the deformability and consolidation characteristics of soft Bangkok clay. For comparison, a series of stress-path-controlled triaxial consolidation tests (tri) were carried out on good quality samples of Bangkok clay taken from the same testing sites and imposed with the same loading conditions as the screw plate tests. Undrained and drained moduli and coefficients of consolidation were obtained from the stress-path-controlled triaxial consolidation tests and were compared with the corresponding values of the screw plate test. In addition, the ultimate bearing capacity was derived from the pressure–deformation relationships of the screw plate test results. A graphical method was used to compute the coefficient of consolidation from the screw plate tests and from stress-path-controlled triaxial consolidation test results. The compressibility data were also obtained from conventional oedometer tests (oed). Both cv (SPLT)/cv (tri) and cv (SPLT)/cv(oed) ratios compared favorably with the cv (field)/cv (laboratory) ratio obtained from past investigations. The data from pressure–settlement–time relationships of the screw plate tests were used to successfully predict values that compared favorably with the measured values at each stress level. The pressure–deformation–time relationship from stress-path-controlled triaxial consolidation tests were also evaluated, and they indicated behaviour similar to that of the screw plate test results. Soil parameters obtained from screw plate tests were subsequently used to predict the settlement of two test embankments, giving fairly close agreement with the observed values. Key words: soft clay, settlement, deformation, consolidation, screw plate test, triaxial test, embankment, prediction, stress path.

Mechanical Characteristics of Ningbo Marine Deposit Soft Clay under Different Stress Paths

2011 ◽  
Vol 250-253 ◽  
pp. 2093-2097
Author(s):  
Chen Bin ◽  
Jun Neng Ye ◽  
Gan Bin Liu
Keyword(s):  
Effective Stress ◽  
Mechanical Characteristics ◽  
Axial Strain ◽  
Soft Clay ◽  
Stress Path ◽  
Shear Mode ◽  
Test Results ◽  
Total Stress ◽  
Consolidation Pressure ◽  
Marine Deposit

Based on a series of consolidated-undrained stress path tests, the mechanical characteristics of Ningbo marine deposit soft clay under K0 consolidation condition are systematically studied for different consolidation pressure, i.e.,60, 120 and 200kPa, in the GDS stress path triaxial system. Three kinds of stress path, i.e., DE (increase p), DG(constant p) and DF(reduce p), are carried out, and the characteristics of stress-axial strain relation, stress path and strength under different stress paths are compared. The test results show that the effective stress paths under consolidated-undrained shear are mainly related to initial consolidation, and the controlled shear mode has evident effect on the effective stress paths. In addition, the stress path has a certain influence on both the total stress and the effect stress strength.

scholarly journals Determination of Creep Properties of Clays from VRS Oedometer Tests

2019 ◽  
Vol 38 (2) ◽  
pp. 1857-1871 ◽  
Author(s):  
Tim Tapani Länsivaara
Keyword(s):  
Soft Clay ◽  
Complex Stress ◽  
Soil Parameters ◽  
Rate Variation ◽  
Additional Parameter ◽  
Creep Properties ◽  
Oedometer Test ◽  
Wide Range ◽  
Oedometer Tests

AbstractThe determination of creep properties still relies almost entirely on the incrementally loaded oedometer test introduced about 100 years ago. Although the simplicity of the test assures a robust evaluation of soil parameters, it also introduces some shortcomings like discontinuity of the evaluated parameters and the long duration of the test. In this study, the performance of the variable rate of strain (VRS) oedometer test for determination of creep properties of a sensitive soft clay is studied. The results from a comprehensive test series of VRS oedometer tests on a soft sensitive clay is presented. Three different setups for the strain rate variation were used, and each test was repeated thrice. The tests showed good consistency and yielded equal creep parameters compared to values from traditional incrementally loaded (IL) oedometer tests. The tests further verified that it is possible to describe the complex stress dependency of creep parameters with just one additional parameter to the primary deformation parameters. Compared to the IL tests, the VRS tests offers a faster determination and continuous creep properties for a wide range of stress.

scholarly journals Effects of sampling disturbance in geotechnical design

2019 ◽  
Vol 56 (2) ◽  
pp. 275-289 ◽  
Author(s):  
Guan Tor Lim ◽  
Jubert Pineda ◽  
Nathalie Boukpeti ◽  
J. Antonio H. Carraro ◽  
Andy Fourie
Keyword(s):  
Soil Mechanics ◽  
Soft Clay ◽  
Excess Pore Pressure ◽  
Soil Parameters ◽  
Test Results ◽  
Sample Quality ◽  
Laboratory Test Results ◽  
Geotechnical Design ◽  
Pore Pressure Response ◽  
Shallow Footing

This paper describes an experimental study of the effects of sampling disturbance in an Australian natural soft clay and the consequences of different sample quality on the representativeness of soil parameters used in geotechnical designs. The paper is divided into three sections. Laboratory test results obtained from specimens retrieved using three different tube samplers as well as the Sherbrooke (block) sampler are first described. Then, the sample quality assessment, using available indices proposed for soft soils, is presented. It is shown that sample quality varies with the stress paths and boundary conditions applied in laboratory tests. Finally, mechanical soil properties derived from specimens retrieved using the different samplers are used in the prediction of two classical problems in soil mechanics: the settlement and excess pore pressure response underneath an embankment as well as the settlement and bearing capacity of a shallow footing. These two examples are used here to highlight the consequences of poor sampling in practice.

scholarly journals Settlement analysis of the Gloucester test fill

1976 ◽  
Vol 13 (4) ◽  
pp. 339-354 ◽  
Author(s):  
K. Y. Lo ◽  
M. Bozozuk ◽  
K. T. Law
Keyword(s):  
Experimental Program ◽  
Canadian Forces ◽  
Test Results ◽  
Time Rate ◽  
Coefficient Of Consolidation ◽  
Total Settlement ◽  
Induced Stresses ◽  
Secondary Compressibility ◽  
Settlement Analysis ◽  
Test Embankment

This paper reports the observation and analysis of the rate and magnitude of settlement under the test embankment at Canadian Forces Station Gloucester. The embankment has been in existence for 7 years and, because of extensive instrumentation, a sufficiently complete record has emerged. An advanced finite element method has been used for the computation of the induced stresses in the foundation soil.Both block samples and 5 in. (12.7 cm) diameter Osterberg samples were recovered at various depths from the site. An experimental program, including the use of the 6 in. (15.2 cm) Rowe cell, has been carried out and an analysis of the test results based on the Gibson and Lo theory. The test results have also been used in the estimation of the field performance.From the present study it is found that: the coefficient of consolidation and the primary and secondary compressibility can be adequately determined from samples of size 4.5 in. (11.3 cm) diameter by 2 in. (5.1 cm) high or larger; the secondary compression contributes significantly to the total settlement for the soil considered; and the Gibson and Lo theory predicts fairly accurately both the time rate and magnitude of settlement in the field.

Effects of Stress Path and Stress History on the Stiffness of Reconstituted London Clay

1986 ◽  
Vol 2 (1) ◽  
pp. 139-144 ◽  
Author(s):  
J. H. Atkinson ◽  
J. S. Evans ◽  
D. Richardson
Keyword(s):  
Stress Path ◽  
Triaxial Tests ◽  
Soil Parameters ◽  
Stress History ◽  
Strain Behaviour ◽  
Reconstituted Soil ◽  
Path Dependent ◽  
London Clay ◽  
Soil Behaviour

AbstractSoil behaviour is stress history dependent and stress path dependent and soil parameters, particularly those for stress-strain behaviour, measured in conventional triaxial tests may not represent the behaviour of soil in many civil engineering works.To obtain more realistic parameters it may be necessary to conduct laboratory tests which more closely represent in situ conditions before and during construction.The paper describes equipment developed at The City University to carry out stress path tests simply and economically. A series of CU triaxial tests and stress path tests on reconstituted soil illustrate the dependence of measured soil parameters on stress history and stress path.

In situ estimation of the coefficient of consolidation in clays

1990 ◽  
Vol 27 (1) ◽  
pp. 58-67 ◽  
Author(s):  
Mohammed G. Kabir ◽  
Alan J. Lutenegger
Keyword(s):  
Key Words ◽  
Pore Pressure ◽  
Reference Values ◽  
Time Factors ◽  
In Situ Tests ◽  
Coefficient Of Consolidation ◽  
Oedometer Test ◽  
Undisturbed Samples ◽  
Oedometer Tests

An investigation was conducted to demonstrate the applicability of cylindrical piezocone and flat piezoblade tests for providing reliable estimates of the coefficient of consolidation in clays. Coefficients of consolidation were calculated from piezocone dissipation tests for different degrees of consolidation using theoretical time factors to provide a comparison with laboratory oedometer tests. Three techniques were developed to calculate the coefficient of consolidation from piezoblade dissipation tests. Results from in situ pore pressure dissipation tests were compared with laboratory oedometer tests performed on undisturbed samples oriented in both the vertical and horizontal directions, to provide reference values of cv and ch. The results of investigations conducted at several clay sites are presented. Key words: in situ tests, piezocone, piezoblade, coefficient of consolidation, oedometer test, clays.

Characterization of a smear zone around vertical drains by large-scale laboratory tests

2000 ◽  
Vol 37 (6) ◽  
pp. 1265-1271 ◽  
Author(s):  
J S Sharma ◽  
D Xiao
Keyword(s):  
Large Scale ◽  
Soft Clay ◽  
Excess Pore Pressure ◽  
Laboratory Model ◽  
Clay Layer ◽  
Prefabricated Vertical Drains ◽  
Vertical Drains ◽  
Undisturbed Samples ◽  
Oedometer Tests ◽  
Excess Pore

Installation of prefabricated vertical drains using a mandrel causes disturbance of clay surrounding the drain, resulting in a "smear" zone of reduced permeability. In this paper, an attempt is made to characterize the smear zone using large-scale laboratory model tests. Two tests, simulating the cases of "no smear" and "with smear," were conducted. Excess pore-water pressures were monitored at seven different locations along the radial direction. In addition, undisturbed samples were collected at various locations in the clay layer for conducting oedometer tests. The distribution of excess pore pressure due to drain installation gave a clear indication of the extent of the smear zone. The effect of reconsolidation on the properties of clay was found to be much greater than that of the remoulding of the clay. The extent of the smear zone was also confirmed from the change in permeability of the clay layer in the smear zone obtained from oedometer tests. The radius of the smear zone is about four times that of the mandrel, and the horizontal permeability of the clay layer in the smear zone is approximately 1.3 times smaller than that in the intact zone.Key words: consolidation, permeability, smear zone, soft clay, vertical drains.

A Change of Undrain Shear Strength of Soft Ground during Consolidation Process

2014 ◽  
Vol 513-517 ◽  
pp. 269-272
Author(s):  
Yeong Mog Park ◽  
Ik Joo Um ◽  
Norihiko Miura ◽  
Seung Cheol Baek
Keyword(s):  
Shear Strength ◽  
Soft Clay ◽  
Confining Pressure ◽  
Triaxial Tests ◽  
Test Results ◽  
Exponential Equation ◽  
Consolidation Process ◽  
Degree Of Consolidation ◽  
Clay Ground ◽  
Strength Increment

The purpose of this study is to investigate the undrain shear strength increment during consolidation process of soft clayey soils. Thirty kinds of laboratory triaxial tests have been performed using undisturbed and remolded Ariake clay samples with different degree of consolidation and 5 kinds of confining pressure. Test results show that well known linear equation proposed by Yamanouchi et al.(1982) is overestimated the strength of undisturbed soft clay ground in the process of consolidation. A new simple and reasonable exponential equation proposed in this paper.

scholarly journals Perbandingan Pengujian Konsolidasi Menggunakan Alat Rowe Cell dan Oedometer pada Tanah Lanau Lunak

2020 ◽  
Vol 22 (2) ◽  
pp. 149-155
Author(s):  
Iskandar ◽  
Rabiya
Keyword(s):  
Pore Water Pressure ◽  
Water Pressure ◽  
Soft Soil ◽  
Soil Samples ◽  
Soil Parameters ◽  
Soil Consolidation ◽  
Test Results ◽  
Soft Soils ◽  
Better Than ◽  
Rowe Cell

Soil consolidation testing using an oedometer and rowe cell. Oedometers are often used on clay and soft soils. However, in the development of the rowe cell device, the results of lowering soft soil were better than the oedometer. The advantage of this rowe cell is that it can determine the saturation value of the soil samples tested. The rowe cell tester can measure the pore water pressure at the beginning and end of each consolidation stage. This rowe cell can provide suitable settlement for soft soils. This consolidation test to obtain soil parameters such as Cv and Cc by using the rowe cell tool. After that, from the test results, the two tools were compared.

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