Predicting the small strain shear modulus of coarse-grained soils: Fid-Bau Portal

Predicting the small strain shear modulus of coarse-grained soils

Liu, Xingyang / Zou, Degao / Liu, Jingmao / Zheng, Bowen

Abstract Coarse-grained soils are important geotechnical materials widely used in construction. The contribution of particle size distribution on the small strain shear modulus G max of coarse-grained soils has not yet been fully recognized. This paper presents an experimental investigation into the effects of the uniformity coefficient C u and the mean particle size D 50 on the small strain shear modulus of coarse-grained soils. To this end, a series of shear wave velocity tests were conducted at different confining stresses and void ratios on reconstituted specimens covering a wide range of particle size distributions. All tests were performed by taking advantage of a custom-developed measurement device in a large-scale triaxial apparatus. The results demonstrate that C u and D 50 have pronounced but opposite effects on G max. Specifically, G max decreases with C u and increases with D 50. The effects of C u and D 50 were then quantified to generate two types of empirical equations, type-A and type-B, that are representative of a broad family of G max equations accounting for the influence of particle size distribution. The equations are tuned based on model parameters A, x and n. In both equations, n is a function of C u. The difference between the two types of equations is that x is the function of C u and D 50 and A is the function of C u in the type-A equation, while x is constant and A is the function of C u and D 50 in the type-B equation. The proposed equations for predicting G max were used to produce acceptable estimates for both coarse-grained soils in this study and from existing literature. The findings acquired from this study are expected to provide a reference for estimating the small strain shear modulus of coarse-grained soils at the beginning of the project when the test data have not yet been obtained.

Highlights • We conducted shear wave velocity tests using a newly developed device. • The effect of particle size distribution on small strain modulus of coarse-grained soils was examined. • The predictive models incorporating the effect of particle size distribution were presented. • The empirical expressions developed in this study generated accurate predictions.