Limit Equilibrium Method And Flac Analogy Method Of Slope Stability Research

With the rapid development of the national economy, a lot of projects encounter problems of the slope stability. Different Slope structure, its deformation and failure modes of the slope are different, the control measures are also quite different.Therefore, it is necessary for the systemic research on the stability factors and the stability evaluation of slope, to meet the requirements of the project construction and the protection of life and property security.Through a summary analysis of existing data, this paper introduces rock constitutive model and yield criterion. Then, the slope stability factors are classified and summarized, and the slope stability evaluation are summarized.To the slope, using two-dimensional finite difference method researches its four profiles and using two-dimensional limit equilibrium method researches slope's.failure mechanism and evaluates the slope overall stability.Main tasks:Use limit equilibrium method to research the four profiles, to judge the slope stability. Calculation of potential slip surface of slope safety factor synthesize Simplified Bishop, Fixed Janbu, M-P,Spencer to overcome deviation.Use rigid body limit equilibrium method to search the potential sliding surface of each profile, and contrast of FLAC method.Use strength reduction method to analyze deformation mechanism of the slope. Comprehensive evaluate the slope overall stability.Compared safety coefficient of rigid body limit equilibrium method with FLAC method, integrated judge the slope stabilityEstablish two-dimensional finite difference numerical model of the four profiles, and analyze relationship between stress and deformation of the slope's natural status and excavation status.Analyze the slope stability.Main conclusions:(1)Location of the most dangerous slip surface searched by rigid body limit equilibrium method and location of the shear strain rate area and plastic zone displayed by simulation consistent.Use strength reduction method to research the first profile,and juxtapose shear strain rate and the degree distribution through the plastic zone to analyze deformation mechanism. On the whole, potential sliding surface of natural slope and excavation slope locates the junction of weak weathered rock and weathered rock.(2)According to the results of the two-dimensional limit equilibrium analysis, except the third profile, other profiles of natural slope and excavation slope are stable.(3)Use two-dimensional numerical calculation based on FLAC analyzes the slope. The maximum and minimum principal stress which rock suffered is mainly compressive stress, stress occurred little change after excavation, the stress concentration occurred in some parts. Deformation of excavation surface points to unloading free surface after excavation. Deformation of All the regional is uniform and has the same regularity. Because slope is steep after excavation and weathered rock is thick, Joint displacement caused by rock rebound after unloading. Range of plastic zone is small and distributed the middle to the top of the slope.(4)In the analysis of engineering examples, location of the most dangerous slip surface searched by rigid body limit equilibrium method and location of the shear strain rate area and plastic zone displayed by unit reduction method consistent.It can be used to determine the location of the most dangerous slip surface when the slope sliding., to provide the basis for reinforcing slope reinforcement.(5)Results of limit equilibrium method and FLAC method show that:the safety coefficient by FLAC is greater than of the limit equilibrium method, the value of about 5%-10% greater. Based on result,the safety coefficient is closed related with the mesh,in general, the more intensive the grid, the greater the accuracy.(6)FLAC considers model boundary constraints, initial stress, elastic and plastic deformation and yield criterion. So, it is more perfect than rigid body limit equilibrium. In specific project, analysis of slope's stress and deformation is much more important than safety factor of researching the slope's general stability.