Undrained Deformability and Strength Characteristics of Soft Bangkok Clay By the Screw Plate Test
Eighteen screw plate tests were carried out using 10-in. 25.4-cm diameter plate, and three types of laboratory test were performed, namely, 18 unconfined tests, 31 unconsolidated-undrained triaxial tests, and 18 one-dimensional consolidation tests. The sampling and testing were carried out at three sites inside the campus of the Asian Institute of Technology in the soft clay layer. At each site, six screw plate tests were performed at depths of 2.50, 4.50, and 6.00 m, and three boreholes were made to take 60-cm-long Shelby tube samples at the test levels. The screw plate test results were calibrated with unconsolidated-undrained (UU) triaxial test results and the bearing capacity factor Nc was found to be 11.00 while the undrained modulus factor K was found to be 0.61. The screw plate test results were also correlated with the unconfined compression (UC) test and one-dimensional consolidation test in this study as well as with the vane shear test and pressuremeter test results from previous investigations. Furthermore, the pressuremeter-settlement-time relationship was evaluated, and it was found that the logarithm of settlement rate, log s, decreased linearly with the logarithm of time, log t, and increased linearly with the logarithm of the stress level, log P'.