非饱和无粘性土的动剪切模量

Dynamic Shear Modulus of Partly Saturated Cohesionless Soils

影响无粘性土的动剪切模量的因素很多,过去认为主要因素只是有效应力和孔隙比。然而本文试验研究表明,对于细粒无粘性土,饱和度将是主要因素之一。非饱和无粘性土颗粒之间的毛细压力使土颗粒间的有效应力增加,从而使动剪切模量增加。对于小应变幅G_o值,存在一最佳饱和度,这时G_o值的增大达到最大值。最佳饱和度和对应的G_o值的增大与土的有效粒径有关。当应变幅增大时,比值G/G_o随应变幅增大而减小,即这种使G值增大的非饱和效应会随应变幅增大而减弱。

Among several factors affecting dynamic shear modulus of cohesionless soils, only two, i.e., effective stress and void ratio, were impovtant in the literature. However, this experimental study shows that, for fine-grained cohesionless soils, degree of saturation can not be overlooked. Capillary pressures between soil particles induce effective stress, consequently, increase the dynamic shear modulus. There exists an optimum degree of saturation that varies with effective grain size, at which increase in value of GO reaches its maximum. As shear strain increases, the ratio of G/G0 decreases, and the capillary effect on dynamic modulus reduces.