The Limit Analysis Of Slope Engineering Stability

This paper studied the plastic limit analysis of slope and supporting structures stability. The upper bound solutions were discussed from the application of the nonlinear failure criterion, the discrimination of the shape and position failure surfaces and the dynamic and static stability of slope and retaining structures. From limit analysis of nonlinear failure criterion applied position and shape, fracture surface of the general, slope and to supporting structure dynamic and static stability analysis of slope and discusses the supporting structure plastic mechanics limit analysis limit solutions.1. The non-linear failure criterion proposed by Baker is a generalized geotechnical strength criterion, and the conventional criterion such as M-C, Griffith and Hoek-Brown failure criterions are all special cases of it. Three non-dimensional parameters can be obtained through triaxial test, and an additional advantage of this form is that the parameters {A, n, T} have clear physical significance. In particular, A is a scale parameter controlling the magnitude of shear strength, Tis a shift parameter controlling the location of the envelope on theσaxis and representing a non-dimensional tensile strength, and n controls the curvature of the envelope. Here, based on the Baker criterion, we studied the slope dynamic and static stability with upper bound theorem. Meanwhile, the optimal solutions are also advised by multivariable expression. An example is given to prove that the theory. The result shows the stability factor increase with the increase of non-dimensional parameter A and T; The yield acceleration increase with the increase of height and slope angle.2. According to the upper bound method and vertical slices method, and assuming the slope material obeys M-C criterion, the internal and external works are calculated respectively by dividing slope body into blocks with regarding the potential sliding face as a group of several sectional planes. Then the multivariate function to calculation critical height of slope is established and optimized by mathematical method, which is determined to the critical height and sliding face shape. Through the example analysis and comparison with the previous research, the results show that the method in this paper is reasonable and effective, and can be used to determine the potential sliding surface and discriminate slope stability.3. A new approach is used to discuss seismic stability and failure surfaces positions of gravity retaining wall. When the wall slope angle increases more than a defined value, the backfill has failed along two planes. Accordingly, we investigate the condition for two failure surfaces appearance. In order to overcome shortcoming which is not taken into account the action of seismic on resistance structures, the wall and backfill soil are considered as a whole system under conditions of plane strain. Calculating the internal and external works, the function of two variables which are determined to positions of two failure surfaces to evaluate the yield acceleration is established and optimized by mathematical software. Numerical calculation is carried out to illustrate the effect of parameters on seismic stability and failure surfaces.4. As a new anti-slide structure, the embedded anti-slide pile is often used in treatment engineering of landslide. There are two parts of calculation for the design of embedded anti-slide pile, including the ant-slide pile of resistance and location. In the anti-slide pile resistance analysis, the resistance can be estimated by plastic mechanics limit theorem, assuming typical failure mechanism for slopes reinforced by pile. In the calculation of the ant-slide pile position and buried length analysis, the internal and external works are calculated respectively by dividing slope body into blocks with regarding the potential sliding face as a group of several sectional planes. Then, the multivariate function to calculation critical height of slope is established and optimized by mathematical method. Through the example analysis, the results show that the ant-slide pile position and buried length and some other factors influence the resistance and safety factor to some extent.5. Based on the deformation characteristics of composite ground under the flexible foundation, the composite ground is divided into four parts, including fill, cushion, composite foundation, and underlying layer. Through the analysis of a typical element, a simplified analytical model, which considers the above four parts as an interactive system, allows for the relative movement between piles and soils and assumes different settlements of foundation soil at the same level plane, is presented. And then according to the compatibility of stress and deformation on the interfaces between these four components, the formulas on settlement and stress ratio of pile-soil, which is used to characterize the behaviors of the composite ground, are derived. Finally, it is demonstrated that the results from this solution are in accordance with the measured ones of a project. So the proposed method can reflect the working behaviors of composite ground under the flexible foundation favorably.6. We studied the advance diagnosis of the high cut slope stability, the reinforcement method of pre-reinforced pile and pre-stressed anchorage, and the critical acceleration and permanent displacement of failure system under seismic are studied. Meanwhile, the optimal solutions are also advised by multivariable expression. At last, an example is given to prove that the theory. The result shows both slope stability and load of pre-reinforced pile except for the critical acceleration are both effected greatly by the cutting method effect.