Thesis (M.Eng.)--Chulalongkorn University, 2006

The elastic shear modulus G[subscript max] is a required parameter for analyses of the dynamic and small strain geotechnical problems. The objective of this research was to evaluate the effect of stress-induced anisotropy on elastic shear modulus of a sand specimen by using bender element technique. A number of isotropically and anisotropcally consolidated drained triaxial compression tests were conducted on loose and dense sand specimens. These specimens were prepared by air-pluviation method. In this study, the measurement of shear wave velocity was performed in two phases, i.e., during consolidation and shearing. It was fund that the elastic shear modulus mainly depended on the mean effective stress and void ratio and rather independent of the level of the deviator stress. The elastic shear modulus was affected by consolidation stress ratio K (stress-induced anisotropy) slightly. This was observed for both loose and dense specimens. The results also showed that the paths of G[subscript max] p' during shearing were almost similar to the one that was obtained during consolidation in both isotropic and anisotropic tests. Based on this experimental data, the empirical equation was proposed to express G[subscript max] as a function of the void ratio and the mean effective stress p' for the sand tested.