Study On The Mechanical Properties Of Fengshuigou Tailings Sand And Dam Body Reliability

Taking the Fengshuigou tailings reservoir as the research background,this paper analyzes the physical and mechanical characteristics of tailings sand through triaxial shear tests,and uses the measured mechanical parameters for stability analysis and reliability evaluation of the tailings dam.The main results are as follows:The high-frequency vibrating machine was used for indoor screening analysis of two types of Fengshuigou tailings sands.The two sand samples were determined to be tailings coarse sand and tailings fine sand.The Consolidated undrained shear tests were performed on coarse sand and fine sand by a triaxial shear tester,the result shows:(1)For tailings fine sand,When the confining pressure does not change,With the increase of the axial strain,the pore pressure first increases and then decreases,and the shear strength of the tailings fine sand is greater;As the dry density increases,the internal friction angle gradually increases and the cohesive force decreases slightly.(2)When the dry density does not change,as the confining pressure increases,the later the peak of the failure occurs,the greater the shear strength of the tailings fine sand.(3)As Compared with fine sand,the triaxial shear deformation of coarse sand is basically the same as that of fine sand,but as the dry density increases,the internal friction angle gradually increases,and the cohesive force gradually increases.(4)Furthermore,according to the Duncan-Chang model,eight mechanical parameters were calculated.The k value of the tailings coarse sand is 217.72,and the k value of the fine sand is 136.77,which is much smaller than the k value of the coarse sand.The n and m values of tailings coarse sand are slightly smaller than the n and m values of tailings fine sand.Compared with Kur and Kb,the values of tailings coarse sand are larger than those of tailings fine sand.In addition,the relationship between tailings sand,elastic modulus and Poisson's ratio was studied.With the increase of confining pressure,the E50 and V50 values of tailings sand are generally increasing.With the increase of dry density,The overall values of E50 and V50 are also increasing.The fitted value of E50 of tailings sand is larger than that of coarse sand,while the V50 of fine sand is slightly lower than the fitted value of V50 of coarse sand.After comparative analysis of the stress-strain curves of coarse sand and fine sand,comparison of the eight parameters of the Duncan-Chang model and the elastic model parameters,it is found that the triaxial strength of coarse sand is greater than that of fine sand.According to the test parameters obtained from the triaxial test,used"Slide" software to perform stability analysis and reliability research on the tailings dam with a dam height of 70 to 142 meters,The safety factor obtained through simulation verifies the stability of the tailings dam.