Mechnical Experimental Research And Strength Reconstruction Mechanism Of Soil-rock Mixture Mass In Surface Coal Mines

This paper researched on the physical and mechanical properties of the mixed rock-soil material in the dump of open-pit mine,based on timeliness slope theory,consolidation theory,limit equilibrium theory and Mohr-Coulomb criteria.(1)The auther put forward a new improving in-situ shear test for the mixed rock-soil material after analyzing two kinds of in-situ tests,push-shear test and load-shear test.According to the compression theory,the converted gravity of the dumping material and porosity variation model,the settlement formula of the mixed rock-soil material and the formula of effective shear strength were established.(2)Besides,the dissertation put forward the structure system of the corresponding impact factors considering the affecting factors in the remodeling process,and established the shear strength formula the mixed rock-soil material based on the Mohr-Coulomb criteria.The essay also described the basic failure forms of the mixed rock-soil material combining with the shear failure model.Remodeling experiments revealed the relationships between cohesion and remodeling time and pressure: the cohesion of the mixed rock-soil material resulting from the growth of remodeling pressure was growing with quadratic function and the cohesion of the mixed rock-soil material resulting from the growth of the remodeling time was decreasing logarithmic.(3)According to the size effect and the distribution density of the mixed rock-soil material,the mechanical equations of two failure modes,which are shear failure and rolling instability when bigger block rock existed,were established.Based on the limit equilibrium theory,the essay put forward the modified calculation formula of stability coefficient of dumping site with arc-landslide,and evaluated the stability of the dumping site in different bulk distribution conditions using the numerical simulation method.The essay revealed the two factors of block ratio and bulk concentration on mixed rock-soil material slope stability influence.Based on the operating procedures of dumping sites and distribution law of mechanical property of the mixed rock-soil material in different layers,the essay get the change rule of the dynamic stability of dumping sites according to analyzing the development of dumping sites stability in two methods,multilayer parallel development of dumping and dumping with layer by layer.(4)The dissertation established mechanical model based on the inclined structure of Longqiao dumping sites and put forward the discrimination condition for self-locking criteria.After analyzing the practical condition,Longqiao dumping sites met the condition of locking in top basal as well as bottom basal but the middle basal was unlocking.Besides,the effective anti sliding force from lower section of dumping site was bigger than the sliding force from the middle section,so the dumping site kept stable.What's more,the essay evaluated the stability of the slope of the Longqiao dumping site in two-dimensional and three-dimensional ways using two kinds of methods of limit equilibrium and finite element analysis and obtained that the stability coefficient of dumping site was decreasing with the growth of the height and the decreasing speed slowed down gradually.