Predicting the Maximum Shear Modulus of Sands Containing Nonplastic Fines

Abstract

There are some attempts to evaluate Hardin’s equation for transition soils, i.e., sand mixed with a systematic increase of fines (particle size≤0.075 mm) content, fc. The most common finding is that maxmium shear modulus, Gmax, decreases with increasing fc, and there are attempts to capture the effect of fc on Gmax by considering Gmax of clean sand as a reference. These are done by (1) developing empirical relations of A, n, c, or d with fc; (2) using equivalent granular void ratio, e*, instead of void ratio, e in Hardin’s equation; and (3) using a critical state (CS) approach. This paper presents 288 resonant column Gmax data for clean Hostun sand and Hostun sand mixed with 5, 10, 20, and 30% nonplastic quartz powder. It is found that when e in a pre-established Hardin equation for clean Hostun sand is replaced by e*, Hardin’s equation can predict Gmax for Hostun sand with fc with good accuracy. Only soil grading properties, e.g., D10 and d50, are required as inputs to convert e to e*. This is a significant advantage over a recently proposed CS approach which requires critical state lines (CSLs) data for each fc.