| Luobogang Slope is at the new site within Hanyuan County, Sichuan Province. It may have stability problems during the new county engineering construction and the process of human activity. And as a result of the deformation and failure characteristics of the slope is unique, there may be a greater hazard to engineering construction .To study deformation and failure mechanism of the slope, analyze its stability, assess its response under supporting, all that is an important practical significance for the new county buildings, and so on.In this paper,"Luobogang Slope in Hanyuan new County, Sichuan Province", is as the research object. Based on the research of regional geological setting, engineering geological environment condition, rock & soil masses structure characteristics, deformation failure evidence and obtaining of rock & soil masses mechanical parameters value of the slope, this paper uses the means of geological formation analysis to study formation and evolution mechanism of the slope, and establishes conceptual model of deformation and failure mechanism of the slope, then, uses the means of discrete element method (DEM) to back-analyze the deformation and failure process of the slope. And then ,in the qualitative analysis of slope stability, this paper uses limiting equilibrium method and FLAC3D numerical calculation method to make an assessment of the slope stability in a variety of conditions, and determine safety reserve is low in the middle & back edge of the slope (landslide-affected zone), and then, based on suggesting two reasonable design scheme ??he slope treatment, uses FLAC3D numerical calculation method to assess support effectiveness of the two scheme, finally, compares to choose a better design scheme. Details and results are as follows:(1)This paper uses the means of geological formation analysis for the slope deformation and failure mode, and then, uses the means of discrete element method (DEM) of numerical simulation for the slope deformation and failure process, which are from the overall deformation of the slope, formation and evolution of tension-caused cracks at back edge of the accumulation of landslide area, formation process of local preservation better rock blocks, full evolution of the disintegration rock blocks, formation process of rift basin at middle edge of the accumulation of landslide area and deformation process of landslide-affected zone area. The results show that:①, the deformation and failure mechanism of Luobogang Slope can be summed up as"multi-layer sliding- crack";②, as there are multi-layer weak intercalations in the slope, and the layers are fluctuations, it makes sliding surface of the rock blocks undulate. Deformation conditions (especially sliding surface conditions) of the rock blocks are so different from one by one that it makes deformation rate of the rock blocks different. During the deformation process, the deformation conditions of the rock blocks will be changed, which will in turn change the deformation rate of the rock blocks. The relationship between deformation conditions and deformation rate is the mechanism for the disintegration of the rock blocks, local preservation better rock blocks after deformation, rift basin, tension-caused cracks at back edge of the accumulation of landslide area and so on;③, when the deformation conditions changes, the deformation of local preservation better rock blocks after deformation is still possible.(2) This paper uses limiting equilibrium method and FLAC3D numerical calculation method to make an assessment of the slope stability in nature, nature + storm, nature ??rthquake and nature + storm + earthquake conditions. The results show that:①, stability of the overall slope is good in natural state;②,in nature + storm and nature + earthquake conditions, the slope can also maintain the basic stability, however, safety reserve is low, it is difficult to reach the request of engineering construction;③,in nature + storm + earthquake state, large-scale area of the slope will fail;④, It is worth noting that the excavation process during construction, especially the partial excavation inducing to expose weak intercalation (including sliding zone) at the slope heel, will reduce the local stability;⑤, water is another important factor for the slope stability.(3) According to the prevention and treatment principles of slope, this paper suggests two reasonable anti-slide pile or anti-slide pile with pre-stressed anchor treatment scheme, then, uses FLAC3D numerical calculation method to assess support effectiveness of the two scheme, and finds that the support effectiveness of the two scheme are good, but the construction cost of the first scheme is higher than the second one, finally, chooses the second scheme as the final treatment scheme.
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