Investigation into small-strain shear modulus of sand-gravel mixtures in different moisture conditions and its correlation with static stiffness modulus

The effects of gravel content, relative density and confining pressure on small-strain shear modulus of sand-gravel mixtures under different moisture conditions were experimentally investigated. The specimens were prepared considering three compaction states, different gravel contents and different moisture contents and tested using the bender element device at three levels of confining pressure. The specimens were then sheared in order to derive triaxial stress-strain curves. The results showed that the maximum shear modulus of mixtures increased with increasing the moisture content, while an increasing-decreasing trend was observed for the pure sand. The maximum shear modulus (Gmax) is more influenced by relative density and confining pressure than moisture content. Then the correlation between Gmax and secant stiffness modulus corresponding to 50% of maximum deviatoric stress (E50), was investigated. The results indicated that the increase in E50 leads to a decreasing trend in Gmax/E50 for different moisture contents and compaction states.