INFLUENCE OF SOIL TYPE ON THE EFFECT OF STRAIN RATE ON SMALL-STRAIN CYCLIC SHEAR MODULUS

概要

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Sixteen different soils were tested in an NGI type simple shear device to examine the effect of strain rate, γ^^・, on cyclic secant shear modulus, G_s, at very small to small cyclic shear strain amplitudes, γ_c ≈ 0.0003-0.01%. The effect of γ^^・on G_s was characterized by strain-rate shear modulus parameter, α_G, and strain-rate shear modulus factor, N_<γ-G>. Parameter α_G describes the slope of G_s-log γ^^・ data for a given γ_c, while N_<γ-G> is α_G normalized by reference G_s. For the clayey soils and their conditions tested α_G ≈ 2.6-6.0% were obtained. For the sandy soils α_G ≈ 0.3-1.2 MPa and N_<γ-G> ≈ 0.5-3.0% were obtained. Data revealed that α_G decreases with increasing γ_c, while N_<γ-G> either slightly decreases with increasing γ_c or stays about constant. The trends of N_<γ-G> with plasticity indes, I_p, liquid limit, w_L, clay content, and activity were examined. It was found that at a given γ_c, N_<γ-G> generally increases with increasing all of these properties and indices. Most consistent and strongest correlations were obtained between N_<γ-G> and I_p and N_<γ-G> and w_L. These two correlations can be useful for the soil dynamics engineering practice and are presented in the paper
社団法人地盤工学会の論文
2003-10-15