Deformation Mechanism Analysis And Optimization Design Study Of Obsequent Rocky Slopes

Sectionâ…¢No. 4 high slope of Tang-Tun expressway, in Huangshan City, Anhui Province, was discussed in this paper. The basic technological route sequence was described as follows: field investigation, establishing conceptual model, analysis and simulation verification of deformation and failure mechanism, evaluation of stability, and treatment design. Conceptual model was established on the basis of different factors, such as engineering geology conditions, symptom of deformation and failure, characteristics of rock mass structure, and external factors. According to this model, it was believed that main model of deformation and failure consisted of toppling-slipping composite deformation. Besides disadvantage interior factor of obsequent layers, inducing factors included heavy rainfall and steep slope excavation. Based on the deep study on the deformation and failure mechanism, using the discrete element theory, the whole process of slope evolution was simulated. Afterwards, stress-strain and stability of slope were comprehensively studied with FLAC simulation and the Limiting Equilibrium Method, which provided the basis to the further design and study. Based on the mechanism of deformation, it gave out two different optimization designs from different treatment notion. At last, though the FLAC and limit equilibrium analysis, the reducing weight design was determined by the comparison of different treatment schemes. It was proved that the selected design accorded with safe demands during construction and daily using. Based on the systematical study above, achievements were obtained as follows.1. With excavation,â…¢-4 high slope's structure characteristics could be comprehended deeply, including the structure region on excavation surface, the engineering geology characteristics and the physical mechanical properties of main structure surface, specially the stability control of obsequent structure surface.2. According to the deformation and failure, which were caused by construction, combining their mechanism analysis, the author proposed toppling-slipping compound deformation and failure conceptual model.3. In order to further prove the accuracy of conceptual model above, DEM was used to carry out the entire deformation evolvement process. As a result, it established comprehensive, direct-viewing and systematic rational conception to the deformation mechanism, scope and process.4. Using the FLAC and the Limiting Equilibrium Methods, a more comprehensive analysis was carried out to this slope's stress-strain and stability during field investigation period. Then it commented the reasons that caused the deformation and failure from the view of the mechanism and internal origin. So this provided comprehensive and objectively estimation for the stability at that time.5. Considering the deformation on this slope, two kinds of treatment methods were given out from the reasons of deformation: one was the strong support scheme without excavation. The other was excavation scheme with protection on the surface, with respective optimization design. And on the basis of the FLAC and the Limiting Equilibrium Method, considering the whole deformation, the plastic areas, the stability at different situations and the construction costs, the excavation scheme with protection on the surface was selected as the final design.