Study On Mechanism And Stability Evaluation Of Earthquake Induced Loess Landslide In Baoji City Weibei Tableland

This paper takes typical loess landslides of Weibei loess tableland in Baoji city as object, studies the mechanism of loess landslide under earthquake in terms of loess and sliding soil,and then the stability is evaluated. The work of landslide stability evaluation and predition in nature condition and under role of the main incentives,is beneficial for prevention of sudden landslide hazard, and provide knowledge and guidance for similar cases.Firstly, based on analysis of relationship between engineering geological conditions and loess landslide, To study the natural form and stability of landslides, landslide identify and distinguish work was carried out, and physical and mechanical properties of loess, as well as the hydrophysical and collapse nature were studied by indoor experiments, with emphasis on influenec of water content.Secondly, in view of stratum structure of loess landslide, the sliding soil was studied in terms of composition, role and sliding surface morphology. As the Pliocene red clay is most important part of slip soil, this paper carried out a series of laboratory tests on it, and with upper loess comparative study the results showed that the Pliocene red clay is of higher clay content, increased plasticity and strong water sensitivity. The water content increases, it reduces the shear strength of red clay on the one hand, especially in the saturated case, the shear strength decreases by 30%; on the other hand, because of its unique hydrophysical properties the soil will swell, disintegrate,which leads to structure damage. Its dynamic failure characteristics and micro structure variation were also studied, there are two distinct failure modes; The microstructure studies show that after shear failure, particles of red clay arranged disorderly, and small pores and its orientation degree increased.Finally, a multiple factors coupling mechanism was put forward for loess landslides, combined with the reality of Baoji city, proposed earthquake-rainfall landslides formation mechanism, which described the role and process of seismic force and rainfall. Based on the machanism, the fuzzy information distribution method was applied to calculate the stability of landslide of DouJitai, combined with the limit equilibrium method to verify the above mechanism. The results show that the stable state loess landslides after earthquake is extremely prone to stability in the subsequent rainfall.