Stability Analysis Of Soil Slope Based On Finite Element Double Strength Reduction Method

In recent years, with the construction of railways, highways and hydraulic infrastructure engineering projects, a large number of slopes were constructed, however slope instability occurred occasionally, therefore slope stability caused widespread concern.In slope stability analysis limit equilibrium methods,such as Fellenius method,Bishop method and Janbu method are most common applied methods. However due to the complexity and uncertainty of geomaterials, limit equilibrium methods can’t fully describe the behaviour of soil material under loads, and there are also significant limitations in these theories, for instance when analyzing slope stability these methods require to assume the position of the sliding surface, and divide the sliding part into pieces, then perform mechanical analysis on each soil piece in order to establish a large number of equations. These methods involve too many assumptions, as a result many geological factors can not be taken into account, plus the solving process is complicated. These defections make these methods can’t simulate slope failure process under real situation. With the rapid development in computer technology, numerical methods are able to conduct better solution, and don’t have to assume the position of sliding surface, so it has became a popular method to analyze slope stability. This thesis use finite element method, combined with strength reduction theory, using ANSYS software platform, accomplished the main contents as follows:(1)Summarized the slope stability analysis theories currently exist, expounded the basic theory of the finite element method and strength reduction method, analyzed the soil constitutive model and the yield criterion. In this thesis, D-P yield criterion is adopted as a basic yield theory for simulation(2)Use a specific slope model as an example to demonstrate the analysis process of finite element strength reduction method, including the slope displacement and the development of slope internal plastic zone when reduction factor was enlarged gradually,and the characteristic of displacement of featured position on slope surface.(3)In order to study the different influence of the two soil shear parameters c and? when maintaining slope stability, in this thesis many slopes of different slope angle were analyzed via three reduction methods, the conclusion indicated when the slope angle is larger than 45°the two shear parameters is suggested to be reduced by the ratio k=0.9, when the slope angle is less than 45°the two shear parameters is suggested to be reduced by the ratio k=0.7.(4)Take a slope engineering project of Bidu highway as an example, established numerical analysis model, then calculated and analyzed the displacement and development internal plastic zone of the slope. The results shows that the safety factor of original slope is 1.07, based on this two sets of reinforcement scheme were put forward, first is to reduce load by excavate secondary slope, second is using anchor reinforcement, the result suggested that the two schemes raised the slope safety factor to 1.27 and 1.36 respectively, recommend apply anchor reinforcement scheme to reinforce the slope.