Nobuaki TAKAGI Strain range dependence on shear modulus of anisotropically consolidated sand Hirofumi TOYOTA Recently, the necessity of accurate ground analysis such as seismic response and vibration analysis is becoming higher with the increase of important structure and neighboring constructions. These analyses require various deformation coefficients in the small strain range. In general, the actual ground is anisotropic because of its deposition process and stress history. However, the effect of this anisotropy on the deformation coefficient in the small strain range is still unclear. In previous studies, the bender element tests (BE tests) and the local small strain tests (LSS tests) were conducted taking note of induced anisotropy. The results showed that the Yoneyama silt exhibited induced anisotropy for saturated soils, but not for unsaturated soils. The objectives of this study is to clarify the effect of induced anisotropy on mechanical properties of sand in small strain range. Toyoura sand having inherent anisotropy was used as testing materials. Anisotropic consolidation (stress ratio K='h/'v constant) is performed to reproduce induced anisotropy. The stress ratio K indicates an isotropic stress state when K=1.0, a compressive stress state when K<1, and an extensive stress state when K>1. The inherent anisotropy is reproduced in Toyoura sand by air pluviation method with sedimentation angles of 0, 45, and 90. Using those specimens, BE and LSS tests were conducted under effective confining pressure of 150 kPa and drainage conditions. The results obtained from the study are summarized as follows: (1) With respect to the initial shear modulus G0, an induced anisotropy that varied with the anisotropic consolidation stress ratio K was observed. The magnitude of the anisotropy is different in unsaturation and inherent anisotropy. (2) With respect to the secant shear modulus Gsec, the strain dependence on the shear modulus varies significantly with the anisotropic consolidation stress ratio K. Induced anisotropy engenders in Toyoura sand with inherent anisotropy regardless of saturated and unsaturated states. Since the induced anisotropy changes the strain dependence on shear modulus, it is necessary for analysis to use a shear modulus considering the stress state of the ground.