Research On The Expansion And Penetration Mechanism And Strength Of Non-penetrating Jointed Rock Masses

This research relies on the National Natural Science Foundation of China project "The weakening of rock bridge mechanical properties and the impact on the strength of non-penetrating jointed rock mass"(project number 11562005),using physical model direct shear test,triaxial test,PFC numerical simulation test three test methods The combination method is used to study the mechanism of non-penetrating jointed rock mass expansion and penetration in non-penetrating joint rock during shearing,and to study the change of mechanical parameters of non-penetrating jointed rock mass and analyze the non-penetrating jointed rock mass.Extended penetration mechanism and strength characteristics under different test conditions.After experimental research,the following conclusions can be drawn.The final conclusions are as follows:1.Through the physical model direct shear test research shows(1)The coplanar non-penetrating jointed rock mass expansion and penetration method is significantly affected by the normal stress,and the larger the normal stress,the greater the damage of the rock mass.The greater the normal stress,the greater the instability strength,peak strength and residual strength of the non-penetrating jointed rock mass,and the shear strength of the rock mass increases.(2)The direct shear test of the coplanar non-penetrating jointed rock mass is carried out until the rock mass is completely destroyed,which proves that the rock mass failure is in the TTTS failure mode.(3)With the increase of normal stress,the damage area of rock bridge in the middle part of rock mass increases during direct shear test,the degree of crack development becomes larger,the stripping material increases,and the damage degree of rock mass becomes larger.2.Through the physical model triaxial test study showsWhen the non-penetrating jointed rock mass reaches the peak shear stress and is in the unstable expansion stage,the C value of the rock mass decreases and the enthalpy value increases,indicating that the cohesive force of the non-penetrating jointed rock mass is weakened,but the friction angle is increased.Large,cohesive force and friction angle change trends are inconsistent.3.Research by numerical simulation test shows(1)Numerical simulation test results of coplanar non-penetrating jointed rock masses show that the expansion and penetration mechanism and strength characteristics of coplanar non-penetrating jointed rock mass are significantly affected by normal stress,joint connectivity,joint relief angle and shear rate;In the direct shear test of different working conditions,the non-penetrating jointed rock mass is mainly caused by the tensile action,and the direct shear failure mode of the coplanar non-penetrating jointed rock mass conforms to the TTTS mode.(2)Numerical simulation test results of different-faced non-penetrating jointed rock masses show that the extended penetration and strength characteristics of the non-penetrating jointed rock mass are affected by normal stress,joint connection rate,joint relief angle,joint inclination angle and shear rate.The impact is significant.