基于二元介质模型的砂类土小应变剪切模量评价方法

To investigate the effect of initial effective consolidation stress σ'_c0, void ratio e, and fines content FC on the small-strain shear modulus G_max of saturated sandy soils, a series of isotropically consolidated bender element tests is performed on three saturated sandy soils with various physical properties. The test results show that the stress exponent n, reflecting the rate of G_max increment due to the enhancement ofσ'_c0, presents a soil-specific constant, and there is a good exponential correlation between n and the synthesizing grain size distribution parameter C_u^s•C_u^f of sandy soils. Fitting parameter A of Hardin model decreases as FC increases, and an exponential correlation is found. But there is no obvious single correlation between fitted parameter d and FC. Combined with the test data of G_max of three saturated sandy soils in the literature, it is found that the stress-corrected small-strain shear modulus G_max/(σ'_c0/P_a)ⁿ for different types of sandy soils decreases monotonically with the increase of the equivalent skeleton void ratio e_sk^*, and a good power relationship between G_max/(σ'_c0/P_a)ⁿ and e_sk^* is then obtained. Generalized Hardin model that allows unified characterization of G_max values for different types of sandy soils with various σ'_c0, e and FC is established based on binary medium model.