Study On Coarse Grained Soil Slope Stability Based On Model Test And Numerical Analysis

A lot of studies have been carried out to analysis the slope stability of clay slope. As we know that there are differences in strength and deformation behaviour between coarse grained soil and clay, and failure law and slip surface shape of coarse grained soil slope are different from clay slope to some extent when slope failure. So far few people studied on this field in the past, and it is worth to pay more attention on this issue.Slope has given birth to a large vertical settlement and lateral deformation before failure occurred. Limit equilibrium method can't exactly analysis slope stability and its result is inaccurate because without taking into account doformation;As a kind of promising stability analysis method, the key of strength reduction method is how to define the failure of slope, that is to say how to define criterion of slope failure. But several criteria proposed are unreasonable in practical application.Based on the former analyses, firstly, indoor model tests of coarse grained soil slope are carried out to study its failure law and slip surface shape;Secondly, deformation behaviour and shape of slip surface of model slopes when failure are simulated using non-linear elastic FEM;Thirdly, the influence of deformation on the slope stability is investigated using FEM;Finally, how to use strength reduction method to analysis stability of coarse grained soil slope is studied.The study results of this paper are as follows:(1) 6 model tests of coarse grained soil slope with various slope ratio and width of holder are carried out using model testing devices to study on the deformation law of certain nodes, the distribution of displacement field within the slope and shape of slip surfaces after slope failure.(2) Limit load of model slopes at limit state is calculated by limit equilibrium method. Deformation, failure law and slip surface shape of model slopes under limit load are simulated using non-linear elastic FEM. The dependability of FEM is proved by comparing the results of FEM and model tests.(3) Using plane-strain FEM, the stress field of the soil slope is found. The influence of deformation on the slope stability is investigated using FEM with arch searching. The law of deformation influencing slope stability is discovered.(4) The key of strength reduction method is how to define the critical failure state of slope. Based on deformation behaviour of model slopes and analysis for a simple coarse grained soil slope, change characteristics of five variables (such as maximum equivalent shear strain e_qmax) with reduction coefficient F_sr during strength reduction are studied using linear shear strength and nonlinear shear strength. A new criterion is put forward by F_sr^e_qmax curve. By comparing its results with other methods, its dependability is proved.