Study On Limestone And Weak Interlayer Mechanical Properties Of Esheng Open Mining High Slope

Ensuring the stability of high slopes is the basis for safe production in the mining of high slope.The stability is very important and the stability of the mine is based on the accuracy of the rock and soil physical and mechanical parameters.Based on the engineering geological survey,we study the mechanical properties of limestone and weak interlayer in the mining area.We obtaine the physical and mechanical parameters of limestone and weak interlayer laboratory test.And the numerical simulation results show that the deformation process of the limestone is consistent with its actual mechanical properties by PFC3 D software,and the model is reproducible and the test sample is effectively reduced.The experimental results are accurate and the experimental results are accurate.The specific conclusions are as follows:(1)As the number of cycles increases,the limestone damage accumulates under the same confining pressure.Then it affects the strength characteristics and deformation characteristics of the specimen.The macroscopic performance is the peak intensity decreases,the peak intensity corresponding to the axial strain increases.After loading and unloading cycles 10 times,the peak intensity decreased by 2.16% and the axial strain increased by 2.97% under 15 MPa confining pressure conditions.(2)As the limestone damage accumulates,the mutual attraction between the adjacent parts of the material and the bite force between the particles are reduced,and the shear strength showed a decreasing trend.After loading and unloading cycles 15 times,the cohesion decreased by 2.7% and the internal friction angle decreased by 1.15%.The increased confining pressure suppresses the accumulation of sample damage to a certain extent under the same number of cycles and a certain confining range.(3)The effect of cyclic loading and unloading on elastic modulus at different starting points is not significant,but the elastic modulus shows a decreasing trend under the same confining pressure and the same number of cycles.When the starting point of the cycle is small,the initial failure of the specimen is dominated by axial pressure,and the crack distribution is relatively uniform.With the increase of the starting cycle,the proportion of shear fracture is increasing and the shear crack accumulates.The proportion of shear crack in the crack distribution is relatively increased and concentrated in the main failure near the surface.(4)Under the same confining pressure and the same number of cycles,the cyclic loading and unloading before the peak will cause some damage to the specimen.With the increase of the number of cycles,the damage will occur in the specimen,and the internal damage will accumulate and damage Degree in the growing,its performance in the macro is the peak intensity of the sample reduced;The greater of the starting point of the cyclic loading and unloading is,the greater of the effect on the strength of the specimen,and the macroscopic representation is that the rate of decrease in peak intensity increases as the starting point of the cyclic loading and unloading increases.(5)In the cyclic shear test of the weak interlayer,the normal stress is an important factor affecting the strain hardening and softening characteristics of the weak interlayer.With the increase of water content and normal stress,the displacement characteristics of the specimen during the ring shear test are mainly changed from shear to main.The strain of the strain hardening characteristic under high normal stress shows that the rate gradually stabilizes the militancy characteristic.The shear stress is affected by the normal pressure and the water content.The higher the normal pressure is,the higher the water content is,the more obvious the strain hardening characteristic is.(6)With the increase of water content,the cohesion and internal friction angle of the weak interlayer are gradually decreased.The residual cohesion of the weak sandwich specimen with different water content is less than the peak cohesive force,and the residual friction angle is larger than the peak Friction angle.The cohesion of the weak interlayer is more sensitive to the moisture content.With the change of the water content,the damage rate of the peak cohesive force is slightly larger than the residual cohesive force,and the damage rate of the peak internal friction angle is slightly smaller than the residual internal friction angle.