Three-dimensional Stability Analysis Of Multi-step High Convex Dump

The dump is the waste soil and rock mass dumped in the open pit mining.Multi-step and high convex dump is a kind of mountain valley dump with special slope geometry.The bottom of the original valley is deeply cut by hills on both sides,so its deformation evolution characteristics are different from those of the conventional dump.Limit equilibrium method is more used to calculate the stability of existing dump design,but the stability coefficient of cross-section design often does not conform to the actual working state due to the strong cutting of valley bottom by terrain,which leads to the early instability of dump.Strength reduction method in numerical limit analysis has become one of the mainstream methods for slope stability evaluation,because it is not restricted by slope topography and geometry.However,the construction of refined three-dimensional numerical model of complex geological bodies still has some shortcomings,such as inaccurate model accuracy and low modeling efficiency,which greatly affects the promotion of numerical calculation methods.In view of the characteristics of multi-step high convex dump,such as complex terrain and special slope shape,the stability analysis of multi-step high convex dump is carried out in combination with experimental research and numerical calculation method.The main research contents and achievements are as follows:?1?The influence of boundary constraint type and slope geometry on the stability of three-dimensional slope is studied.The necessity of three-dimensional analysis of slope stability is clarified by strength reduction method in finite difference software FLAC^3D.The reliability of this method is verified by classical examples.The influence of boundary constraint type and slope geometry shape on three-dimensional slope stability is systematically studied,and the influence of different boundary constraint types and slope geometry shape on critical sliding surface and stability of slope is revealed.?2?Research on fast modeling technology of refined three-dimensional numerical model.Aiming at the problem of constructing three-dimensional numerical model of complex geological body,a fast multi-software coupling modeling process is proposed.Based on the MATLAB language,the interface program is compiled to realize the successful conversion of ABAQUS model to FLAC^3Dmodel.The refined three-dimensional numerical model is established by using the built-in transfer formats of GOCAD,Surfer,Rhino,ABAQUS and FLAC³DD software.The complex three-dimensional numerical model is constructed by the idea of"point-line-surface-volume"modeling.?3?Three-dimensional stability analysis of multi-step high convex dump.Conventional indoor geotechnical tests were carried out to obtain the basic physical and mechanical parameters of the base soil under dry and wet conditions.Laboratory rock tests including rock density test,water absorption test,uniaxial compressive strength test and triaxial compressive strength test were carried out to obtain the density and water absorption of the base rock under dry and wet conditions.The parameters c and?of rate,uniaxial compressive strength,triaxial compressive strength and shear strength were studied.In situ large-scale direct shear tests were carried out on 10 groups of 30specimens to obtain the weight and shear strength parameters c and?of dump under dry and wet conditions.A total of 12 groups of 60 specimens were carried out for heavy compaction tests to obtain the maximum dry density and optimal moisture content of dump.The above indoor and outdoor test methods quantitatively acquire the physical and mechanical indexes of various types of rock and soil in the site area,which provides reliable design indexes for the optimization of subsequent dumping schemes,and also provides an important basis for the selection of rock and soil parameters for other engineering construction in the area.On the basis of generalizing the dump slope into multi-step and high convex piled slopes,a three-dimensional numerical model of the site area is established by using multi-software coupling method,and the present stability of the slope is evaluated by using finite difference software FLAC³DD and strength reduction method,and the slope rate and curvature of the following step-loading parameters are optimized;the arc-original surface composite sliding surface of multi-step and high convex piled slopes is found out.On the basis of state,the spatial evolution mechanism of this type of slope from start-up to instability stage is explained by using multi-point monitoring data of the whole slope in numerical calculation.