Variation of Elastic Modulus in Composite Ground Improved by Sand Compaction Pile with Low Area Replacement Ratios

Poisson's ratio(n), Young's modulus, Shear modulus(G), Bulk modulus(K) and Constrained modulus(Mc) are typical elastic parameters in soil mechanics and have correlation with each other based on the traditional theory of elasticity. These parameters are used to model and analyze geotechnical materials as variables, especially in the case of linear or nonlinear elastic model and elastoplastic model. As composite ground improved by sand compaction pile, however, consist of sand and clay, behavior of clay part and SCP may different from that of pure material, and conventional theory of elasticity does not have validity because original modulus of elasticity cannot be adopted in composite ground. In this study, variation of elastic modulus with increase of the area replacement ratio were identified. In addition, new equation including Poisson's ratio was derived from the basic relation of SCP-composite ground, to investigate the validity of Poisson's ratio as a constant.