Study On The Correlation Between The Shear Strength Characteristics Of Copper Tailings Sand And The Microstructure Parameters Under The Action Of Drying And Wetting Cycles

Copper tailings dam sand,as a waste left over from the production of metallurgical enterprises,appears in various areas in the form of concentrated landfills,resulting in copper tailings dams experiencing a variety of natural climates,and the more typical one is the rainy season,that is,the continuity and Periodic rain pattern.Seasonal rainfall will cause changes in the shear strength characteristics of copper tailings sand,which will affect the stability of the dam.Therefore,this paper takes copper tailings sand,the filling material of copper tailings dam in eastern Hubei,as the research object,analyzes the macro-mechanical properties of copper tailings under the action of dry and wet cycles,and reveals the macro-mechanical mechanism from the meso level.In this paper,the basic physical properties test and triaxial compression test of copper tailings are carried out to analyze the macro-mechanical properties of copper tailings under different dry and wet cycles,and then samples are selected for scanning electron microscopy(SEM),and IPP6 is used based on the test results.Software conducts qualitative and quantitative analysis on the mesostructure of the soil;finally,the gray correlation theory is used to explain the correlation between the mesostructure parameters and the shear strength index,and from the mesostructure level,it reveals that the tailings sand has undergone different drying processes.The essential reason for the change of effective cohesion and effective internal friction angle under the action of the wet cycle.The main research contents are as follows:(1)The basic physical properties of copper tailings sands were evaluated through basic physical property tests,which laid the foundation for subsequent research on copper tailings sands.(2)According to the natural environment and climate characteristics of eastern Hubei,the test parameters required for the dry-wet cycle test were obtained through the dry-wet cycle pre-test,and the characteristics of the moisture content time history curve of the sample in the process of moisture absorption and dehumidification were clarified,and based on This formulates a dry and wet cycle test program.(3)According to the actual working conditions,a triaxial compression test program under different confining pressures,different dry and wet cycle periods,and different matrix suctions was developed.Based on the experimental data,the degree of influence of the dry and wet cycle action on the shear strength under the same matrix suction,different confining pressure,the same confining pressure,and different matrix suction is analyzed.The effective cohesion and cohesion are obtained through calculation and fitting.Decay function of the effective internal friction angle.(4)Based on the results of scanning electron microscopy(SEM)and with the help of IPP6.0 software,quantitative analysis of pore mesostructure parameters with the number of dry and wet cycles,reveals the changes in microstructure parameters under the action of dry and wet cycles Internal reason.(5)Use grey relational theory to establish the correlation between meso-structure parameters and effective cohesion and effective internal friction angle.And found that under the action of dry and wet cycles,the dominant factors affecting the effective cohesion and the effective internal friction angle are the average shape coefficient,abundance and probability entropy.