Study And Application On 3D Limit Equilibrium Method

In our country which is mountainous,more than two thirds of land area are mountains. With the development of economy,the mountain cutting and the soli filling,a large number of slops are being created. According to the statistics of Ministry of Land and Resources, 22,329 landslides occurred in our country in the year of 2010,72.8% of the total number of geological disasters. Based on the Mohr-Coulomb yield criterion and the static equilibrium, two-dimensional limit equilibrium slope stability analysis is widely used,but the two-dimensional limit equilibrium method approximately consideres the slope as a plane strain problem, ignoring the blocking sliding force of the sliding flank surface,so the calculation is too conservative. The slope itself is a real three-dimensional problem.If taking it as a two-dimensional problem,there must be limitations and imperfections,so the two-dimensional analysis should be extended to three-dimensional analysis to make the results of calculation more practical. Based on actual research needs ,three-dimensional limit equilibrium method has been studied in this thesis,and is applied to engineering calculations.The thesis includes the following aspects:1) Build the model of the three-dimensional limit equilibrium of slope stability analysisThe model of the three-dimensional limit equilibrium in this thesis is based on the IWHR method,mainly embodying that mechanical model and geometric model of the three-dimensional limit equilibrium method are be established,the forces on the columns are be partly improved,shear force R is be added onto the row surface,and the size and direction of R are be provided.2)Establish the forces and torque balance equation,and caculate the safety factorStudy the forces on the columns and calculate the normal force N i on the base sliding surface;establish the overall static equilibrium equation on the direction of S;establish the overall static equilibrium equation on the direction of Y;and establish the overall torque equilibrium equation around the y-axis. According to Newton-Raphson method,the safety factor,the angleβbetween the force E on the line surface and the x-axis,the angleρbetween the shear T on the base sliding surface and the plane xoz.3) Establish the search model of three-dimensional slip surfaceEstablish the Bezier sliding surface search model of three-dimensional slip surface,simplifying the control parameters of Bezier S = S ( w, h, v , d , x , y , z ,θ,φ)for using the genetic algorithms to search the most dangerous slip surface.4) Procedure implementation and example testingWrite programme to search the three-dimensional slip surface and calculate the safety factor,and then test the three-dimensional model in this thesis and the reliability of the programme.5) Engineering exampleThis thesis takes the high fill embankment slope of the Kunming Xiaoshao International Airport as stability analysis engineering example to calculate its two-dimensional,three-dimensional safety factors and proposes advice of the slope protection.