Study On Conductivity Response Characteristics And Damage Evolution Of Rock Failure Process

With the continuous development of China's economic construction,there's lots of geological and geotechnical problems are often encountered in the process of engineering construction.On the other hand,earthquakes have occurred frequently in southwest China,and secondary disasters such as rock damage and slopes caused by seismic loads are more devastating.At present,when defining and quantifying the damage process of rock with plastic deformation characteristics,the classical rock damage theory will greatly simplify and cover up the real damage in the rock failure process,it is difficult to describe the details of the rock failure process and causing a certain degree of error.This study discussed the evolution process of rock damage and the response characteristics of electrical conductivity under uniaxial load.The improved rock similar materials were developed to study the coupling relationship between the response characteristics of electrical conductivity and the law of strength variation in the uniaxial compression test.Based on this theory,the finite element modeling of layered rock is studied.The main conclusions are as follows:(1)Taking limestone as the simulation object,the improved rock similar materials have similar structural and failure characteristics to limestone.The electrical conductivity of the material and the sensitivity of resistance collection can be obviously improved by adding graphite powder to similar materials.At the same time,the conductivity ratio of the sample with graphite powder is consistent with that of samples without graphite powder.(2)Under the condition of constant temperature drying,the variation of electrical conductivity would be closely related to the initiation,development,penetration and geometric shape changing of rock cracks.The conductivity of sample firstly increases with the load increasing,and then decreases with the initiation and expansion of new cracks under uniaxial load.The damage evolution law of sample could be obtained through describing the variation of electrical conductivity,while the relationship between the electrical conductivity and the strength variation of sample could be established.(3)On the basis of effective stress principle and electrical conductivity theory,the damage evolution equation based on electrical conductivity is derived,which can better reflect the response relationship between rock electrical conductivity and strength change.The plausibility of the theory presented in this paper was further validated by a comparative analysis of experimental data from other samples and other literature.(4)The finite element model of layered rock is established by using the theory proposed in this paper.The development laws of the layered rocks model damage area were analyzed during the loading process and the conductivity response principle of layered rocks intensity changes was further summarized.The results of the finite element analysis were compared with the theoretical and experimental results to verify the applicability of the theory presented in this paper to the analysis of the damage destruction of layered rocks.