2020 Volume 76 Issue 2 Pages I_279-I_287
The purpose of this study is to propose a method for estimating the deformation modulus that appropriately reflects the effect of stress dependency and drainage condition on the deformation modulus of subgrade soil. A series of cyclic triaxial test combined with the bender element test (CTX-BE test) was performed on five soil materials with different physical properties (Toyoura sand, diluvial sand, decomposed granite soil, alluvial clay, loam) under drained/undrained conditions. The relationship between the shear modulus G, the deformation modulus E and the mean effective stress σm’ under both conditions was obtained. Furthermore, based on the report of previous study that the shear modulus G is strongly affected by the void ratio e, measured G in the CTX-BE test was corrected by the void ratio function f(e), and the G-e-σm’ relationship were more clearly understood. Then, the relational expression E/f(e)=Aσm’n peculiar to the material under different drainage conditions was investigated, and a simple formula estimating deformation modulus was proposed in which the void ratio and the mean effective stress only are given parameters.
