Semi-empirical Model for Estimating the Small-Strain Shear Modulus of Unsaturated Non-plastic Sandy Soils

The shear modulus at small-strain, G(max) is a maximum value of shear modulus for a given stress state and void ratio, and is a key parameter to evaluate the dynamic response of geotechnical structures. However, the laboratory testing procedures for determining G(max) are time-consuming, cumbersome and require elaborate equipment especially for unsaturated soil samples.. semi-empiric.l model is proposed in this p.per th.t c.n be used to estim.te the v.ri.tion of Gm.x with respect to m.tric suction for non-pl.stic s.ndy soils (i.e. I-p = 0 %). The proposed model uses the Soil-W.ter Ch.r.cteristic Curve (SWCC) .nd the she.r modulus .t s.tur.tion condition .long with two fitting p.r.meters zeta .nd xi. The proposed model permits estim.tion of the v.ri.tion of Gm.x with respect to m.tric suction over different zones of the SWCC (i.e. bound.ry effect, tr.nsition, .nd residu.l zones) for v.rious non-pl.stic s.ndy soils. The fitting p.r.meters zeta .nd xi required for the proposed semiempiric.l model c.n be estim.ted from simple rel.tionships derived from the gr.in size distribution curve.