Scale Effect And Slope Stability Of Coarse Aggregates In High Bench Dumps

The establishment of high dump sites can effectively reduce mining land occupation,improve resource development efficiency.The soil body is composed of wide-graded waste rock particles with different particle sizes,and the particle distribution of the wide-graded waste rock during the dumping process is random and fuzzy.Besides,the high-bench dumping site with wide-graded waste rock has obvious particle size grading,which causes the anisotropy and unevenness of the accumulation of the high-bench dumping site.In addition,because of the limitation of the size of the existing coarse-grained geotechnical testing equipment,the large-size waste rock coarse-grained materials need to be scaled before the test,resulting in an obvious scaling effect.So it is difficult to obtain the reasonable strength parameters of the coarse-grained materials of the dump site.This paper relies on the actual high-bench dump site engineering project,using comprehensive analysis methods such as on-site particle size investigation,laboratory test,numerical simulation and theoretical analysis,the research on the scale effect of wide-graded waste rock coarse-grained materials and the stability of high-level dumps has been carried out.The main research results are as follows:(1)Through the on-site particle screening test,the particle size distribution law of bulk coarse-grained materials at the empty surface of the high-bench dump site was studied,and the gradation curve of coarse-grained soil samples at different heights was discussed.With the help of the coefficient of uniformity Cu and the coefficient of curvature Cc,the soil samples at different heights were evaluated,and the obvious particle size classification phenomenon of the high-bench dump site was analyzed.(2)Based on the temporal and spatial discrete characteristics of cellular automata,this paper develops software EPOHHM that can simulate five random distributions.The software can be close to the distribution of different particle groups in the coarse-grained materials,and provides numerical assistance for the triaxial test simulation of the coarse-grained materials and the stability analysis of the high-step dump site.(3)With the help of EPOHHM,combined with FLAC^3Dsoftware,a triaxial numerical simulation sample that can characterize the heterogeneity of bulk rock and soil materials was constructed,and a large-scale triaxial numerical simulation test of typical coarse-grained materials was completed.The whole process of failure of the coarse-grained material numerical sample in the test is revealed,and the relationship between the maximum particle size d_maxof the coarse-grained material and its strength parameters and deformation parameters is discussed.In this way,the scale effect of coarse-grained materials on strength and deformation is studied.(4)Narrow-graded coarse-grained material groups were used to characterize the particle size distribution of high-step dumps.Taking into account the unevenness and randomness of the distribution of coarse-grained materials in each particle group,a numerical calculation model of the high-bench dump was established.Through the analysis of the displacement field and the distribution of the plastic zone of the dump,the stability of the dump slope under the two dumping modes of full section height dump of single-step and full overlay dump of multi-step are systematically studied.A refined analysis method for the stability of high-bench dumps with wide-graded waste rock is proposed.The research results of this paper can provide a way of thinking for the study of the scale effect of coarse-grained materials,provide guidance for ensuring the long-term stability of dumping sites with obvious particle size classification,and provide a reference for future analysis of such engineering problems.