Research On Mechanical Properties Of Marble Under Unloading Conditions And Numerical Simulation

Compared with the common shallow rock,the deep rock which with a more complex geomechanical background (such as high field stress, Highland temperature, high-karst water pressure, strong mining disturbance),so the rock which reflected significantly different strength characteristics and deformation to the shallow rock when it in the force,how to ensure that the stability of deep rock engineering is the key issues need to be address current.Based on this,we use the geological and excavation environment as the background which the deep marble of Jin ping Hydropower Station in, Relying on the national natural science foundation of china be hold by professor Li Xinping:Study on load and unload mechanical properties of marble in deep stratum and its multi-filed coupling models,Considered the high field stress and unloading environment.analysis and research on the deformation and strength characteristics of marble under unloading conditions,By the laboratory test system and the theoretical analysis,Fitting a power function of strength criterion which applies to the rock samples under the unloading path, the last conduct a simulation under the unloading test of marble by the numerical software,Reached the purpose of mutual authentication with the laboratory test.the following aspects of the study is included in the paper:(1) with research to the process of the test and analysis of the date that on the uniaxial compression,conventional triaxial test and unloading test of the marble in the condition of high geostresses,and get deformation characteristics and the strength criterion of the marble under different test methods,Mainly as the follows:whether it is under loaded or unloaded, the confining pressure have a greater impact on the axial bearing capacity of the rock samples;in the pro-peak unloading and post-peak unloading confining test, the brittle fracture characteristics is shown by the rock samples, Lateral strain is about twice of the axial strain when the sample is destructly,but in the triaxial test, Both are roughly the same.Compared with the conventional triaxial test, the destruction of the rock is caused more easy in the unloading test, and the degree of destruction is more intense,The damage is more obvious caused by the pro-peak unloading than the post-peak unloading confining test,Provides detailed experimental data to establish non-linear strength criterion of the marble.(2) by analysis of the previous method which establish strength criterion of the rock, fitting a power function of strength criterion which applies to the rock samples under the unloading path, comparison Hyperbolic and parabolicstrength criterion, the strength criterion of the power function is more reasonable.(3) Base on the process of the test and analysis of the date, the test of the marble under the unloading conditions is simulated by the finite difference program FLAC3D.the fitting strength criteria is verified correctly. and complement and description of the laboratory test.