Mechanical Properties Test And PFC3D Numerical Simulation Of Sandstone With Single Joint

There are discontinuities with different structures in the engineering rock mass,which make it have the characteristics of discontinuity and anisotropy.Therefore,the mechanical properties of rock mass depend on the mechanical properties of rock itself,and also on the mechanical properties of structural plane and the spatial combination of structural plane to a great extent.Most of the rock masses encountered in the practical engineering are incomplete rock masses.Due to the needs of mineral exploration,energy extraction,transportation,urban underground space and other projects,the research on the mechanical properties of jointed rock masses is becoming more and more important.In order to research the influence of joint on rock specimens under different stress states,laboratory test and numerical simulation of sandstone specimens with single joint are carried out in this paper.The main research contents are as follows:(1)The effect of joint angle and confining pressure on peak strength,anisotropic deformation and failure mode of jointed sandstone under triaxial stress is studied by laboratory conventional triaxial compression test of jointed sandstone specimens with different angle.Combined with realtime acoustic emission system,the failure mechanism of jointed sandstone under conventional triaxial compression is revealed.(2)Based on the results of laboratory conventional triaxial test,the tests of unloading confining pressure and cyclic loading of jointed sandstone specimens with different angle under different confining pressure were carried out.The influence of different unloading rate of confining pressure on the mechanical behaviorand failure mode of jointed sandstone is analyzed.The deformation evolution and failure mode of jointed sandstone under monotonic and cyclic loading,and the influence of cyclic times on the mechanical parameters of jointed sandstone are studied.(3)The parallel bond model in PFC3 D software is used to establish a complete sandstone specimen numerical model.The scanned joint surface is imported into the complete model and the smooth joint contact is installed to generate the jointed sandstone numerical model.Based on the results of conventional triaxial tests in laboratory,the reasonable micro parameters which can reflect the macro mechanical properties of real jointed sandstone samples are selected.The numerical simulation calculation of the conventional triaxial loading path of jointed sandstone was carried out,and the propagation and evolution rule of micro cracks was recorded in real time during the triaxial loading simulation of the numerical model,and the failure characteristics and mechanism of jointed sandstone samples are analyzed from the micro perspective.There are 84 figures,15 tables and 105 references in this thesis.