Characterizing stiffness and strength of soft Bangkok clay from in-situ and laboratory tests

This paper presents some preliminary results of in-situ and laboratory tests on soft Bangkok clay obtained through an internationally co-operation research program. Various kinds of in-situ tests as well as soil samplings were carried out in an attempt to characterize profile of stiffness and strength with depth at two sites, AIT campus and Nong Ngu Hao (NNH) site; the latter is planed to be Second International Airport in Bangkok. The results show that the profile of elastic shear modulus, G(max), was about 5.5 to 11 times of dilatometer modulus, E-D, and the rigidity index, G(max)/S-u, ranged from 300 to 500. The undrained shear strength, S-u, from in-situ vane test can also be correlated to the cone tip resistance using the cone factor, N-KT, of 11 and 17 for AIT area and NNH area, respectively.