The Dynamic Characteristics And Structure Of Loess Under Dynamic Torsional Shear

Loess is a kind of structural soil, which mainly distributed in west China, where the earthquakes happen frequently. The research on dynamic characteristics and structure of loess has become one of the main topics of 21st century. In this paper, we studied the dynamic characteristics, and discussed the law of structural of loess, which located in Dangjiacha, Xiji county, Ningxia province, under dynamic torsional shear. We selected 5 frequency and 3 consolidation pressure in this test.By sorting test data, we have analyzed the effect of the frequency and consolidation pressure on dynamic stress-strain relations, dynamic shear modulus, and dynamic strength of loess. We also discussed the law of structure damage of loess. The test result show that:the stress-strain relationship accord with Hardin-drnevich hyperbolic model, especially in smaller dynamic shear strain range. And, the higher the consolidation pressure, the greater dynamic shear stress are needed, the bigger the dynamic shear modulus, and the higher the dynamic strength, if producing the same dynamic shear strain under the same frequency conditions. When the consolidation pressures are 100kPa and 200kPa, the influence of the frequency on the dynamic stress-strain relationship and dynamic shear modulus shows the opposite regularity.Generally speaking, the influence of the frequency and consolidation pressure on the dynamic characteristics of the loess ascribe to the changing of the structure of loess, which accompany with the damaging of the structure and the forming of the secondary structure of the loess. It mainly discussed the vertical damage variable of the loess which is taken from the landslide back-wall, and the rules of the damage variable in different frequency and consolidation pressure.