Experimental Study on Dynamic Shear Modulus and Damping Ratio of Loess Considering Disturbance

Abstract

Loess is a special kind of Quaternary sediment. The sub-stable skeleton formed by fine grains and salt crystals makes the loess with great risk of catastrophic changes under dynamic action. In order to study the influence of the natural structure of loess on its dynamic properties, the test was conducted on the loess at the near-fault site of the Lishan piedmont fault to analyze the influence of soil structure disturbance on the dynamic properties of loess. The test adopts dynamic triaxial test system. The results show that the soil structure disturbance has a large effect on the dynamic shear modulus of the loess, while it has little effect on the damping ratio. Under low confining pressure, the maximum dynamic shear modulus of original loess is smaller than that of remodeled loess. Under the high confining pressure, the original loess is larger than the remodeled loess. When the confining pressure is 400 kPa, the maximum dynamic shear modulus of the original loess is 93.28 MPa, which is 53.8% larger than that of the remodeled loess. When the dynamic strain reaches 0.15%, the difference between the damping ratio of the remodeled loess and the original loess is less than 0.04, and it can concluded that the soil structure disturbance has little effect on the loess in the Lishan piedmont fault.