Cyclic Simple Shearing Test Simulation Of Interface Between Geo-Materials Based On Strain-softening Model And Study Of Its Mechanical Characteristics

In the field of civil engineering,there will be a variety of material interfaces,which means the contact surface of different materials.Due to the difference of the two sides of the material,there is often a large shear stress and discontinuous displacement near the contact surface,which leads to more complicated stress and deformation states of the material.For example,in tunnel and underground engineering,there exist different types of contact surface between different rock strata,rock mass and lining.The existence of the contact surface has great influence on the stress and strain characteristics of the soil and tunnel lining,and the location of the contact surface is usually the place where the dam is easy to deform.Based on the geotechnical material contact surface as the research object,the single shear test was simulated,combined with the indoor test conclusion analyzes the rationality of the simulation method,the mechanical properties and on the basis of the contact surface under cyclic load is studied,the main research contents and results are as follows:(1)The main theoretical results of strain softening at home and abroad were summarized,and the rationality and reliability of numerical simulation were discussed:(2)By using the strain softening model embedded in the finite difference program,shearing test of the contact surface was simulated.Through the comparison of test results,the rationality and reliability of numerical method were verified.Furthermore,by using the method of single factor analysis,the influence of different factors on the result of the test(the contact surface mechanical properties)were studied.The results show that the strength of the material near the contact surface is the lower envelope of the material strength,and the influence of the cohesion and the internal friction angle is different when the normal stress is different.(3)Based on the numerical model of contact surface shearing test,a cyclic shearing test of soil interfaces was simulated,which explores the failure mechanism and its shear properties of soil interfaces under cyclic loading.Further,results of shearing test and cyclic test were compared and analyzed.The results show that the failure mode of the specimen is different from that in the single shear test,and the specimen will be destroyed gradually with the increase of plastic strain.(4)Through the design of orthogonal test,the sensitivity analysis of different factors affecting the cyclic shear behavior of contact surface was carried out.The results show that the normal stress has a great influence on the test results,and the other factors have different degrees of influence.