Study On The Mechanical Characteristics Of Granular Media And Slope Stability With Super-high Bench Dumping Site

The construction of super-high bench dumping site can decrease substantially mining space and attain the goal of both resource exploitation and environmental benefit. Nevertheless, the super-high bench dumping site which is characterized by the particle size grading is different from the usual soil slope. This thesis studies the grading rules and mechanical characteristics of granular coarse-grained materials in dumping site by using the following methods: the on-site investigation of grain size, laboratory test and numerical simulation. Baesed on the research pobjec of Xiyuanling 413m step dumping site of the Dexing copper mine in Jiangxi province, the slope stability of the super-high bench dumping site with the obvious particle size grading is fully researched. The main achievements of this dissertation are as follows:1)The article analysed the particle size distribution of dumping site according to the on-site experiment of particle size. Meanwhile, the Rosin-Ramuler model was revised and the revised model was verified by use of the result of on-site particle size . The distributed parameter d value of the revised Rosin-Ramuler model was redefined and the relationship beween the d value and the dumping site height was established. This thesis established the function equation beween the undersize relative content at a certain particle size with the slope of dumping site and the height of dumping site.2)With the refitted large-scale direct shear apparatus, the particle breakage experiment of different vertical pressure and different coarse-grained contents had been completed, and the relationship between upright stress and coarse-grained content and the particle breakage index was analysed. and based on that, The stress-broken description model was established. Meanwhile, the particle breakage of saturation samples and unsaturated samples and soaked samples was studied by experiments, and the effect of different moisture contents and long-term soaked to the particle breakage index was analyzed.3)The mechanical characteristics of coarse-grained soil was studied through the large-scale direct shear apparatus, The thesis analyzed the changing regularity of shear stress and strain curve in the different vertical pressure and different coarse-grained contents. the effect of coarse-grained contents and vertical pressure and particle breakage to the internal friction angles of coarse-grained soil was analyzed combining the research results of particle breakage with coarse-grained soil. 4)According to cellular automata method, the HHC-CA model which could randomly simulated three cellular states was developed. And it laid a foundation for the building of virtual triaxial lab with coarse-grained soil and slope computation model of super-high bench dumping site with characterizing the obvious particle size grading.5)This thesis fully provided a new test method for the triaxial numerical simulation test of coarse-grained soil. Based on the HHC-Soil model which derived from the developed the HHC-Soil model, we generated the coarse-grained soil samples of different initial fabric of grain to characterize the heterogeneous and random distribution of coarse-grained soil grain group.Then by means of FLAC-3D,the triaxial numerical simulation tests were completed and the feasibility of virtual triaxial test with coarse-grained soil was verified by use of the indoor triaxial test results. The effect of the gravel contents of samples shear band and samples on the internal friction angle was discussed.6)A new method of slope stability analysis with the super-high bench dumping site which was considered the obvious particle size grading was presented. On the basis of the derivative HHC-Granular model and on-site survey of granular size distribution,the slope model, which was used to carry through the slope stability analysis, was established according to the Xiyuanling 413m step dumping site considering the features of particle size grading. Through the slope stability analysis, The slope security and stability of dumping site with adopting the piling up pattern of“whole section height dump of single-step”and“full overlay dump of multi-step”were discussed.