Seepage And Diffusion Mechanisms Of Blot-grouting Slurry Within Fractured Surrounding Rocks Of Deep Roadway

Bolt-grouting support technology is an effective way to maintain the stability of fractured surrounding rocks in the deep roadway, and it has both theoretical significance and engineering application value to perfect the theory of bolt-grouting supporting and enhance the effect of bolt-grouting supporting through studying the diffusion law of the slurry. This paper takes bolt-grouting supporting roadway engineering in the deep surrounding rocks as the background, makes an integrated use of experiment, theoretical analysis, numerical simulation and field monitoring to cast a deep and systematic study on the permeability evolution characteristic of and diffusion laws of bolt-grouting slurry within fractured rocks. Hence, the following innovative research results and main conclusions have been made:(1) Based on the permeability test theory in the post-peak fractured rock, a triaxial slurry permeability test device and a grouting pressure pumping station with an axial loading system, confining pressure supply system, grouting pressure supply system and data acquisition system was designed, which is matching with the MTS816 Electro-hydraulic Servo-controlled Rock Mechanics Testing System, to develop the triaxial slurry permeability testing system of fractured rocks. The system can accurately measure the permeability of slurry under different post-peak fracture states and confining pressure, which providing an effective testing method to deeply reveal the permeability and the diffusion laws of slurry within fractured rock.(2) The slurry permeability within fractured rocks under different post-peak states, confining pressure and grouting pressure are systematically carried out with the developed triaxial slurry permeability test device, thus the variation of the pore pressure, slurry permeant flux, slurry permeability in the fractured rocks are obtained, combined with the CT scan results of and the tri-linear strain-softening model of the fractured rock, the effect law of the post-peak fracture states, confining pressure and grouting pressure coupling on the slurry permeability evolution are revealed.(3) Utilizing the Navier-Stocks equation in classical fluid mechanics, the equivalent fracture model and the slurry permeability evolution model of the fractured rock are established based on the test results of slurry permeability evolution within the fractured rock, and the relationship between the slurry permeability of the fractured rock and the post-peak fracture states, confining pressure and grouting pressure has been deduced. Embedding the model into the FLAC3 D and COMSOL Multiphysics softwares, the numerical simulation of the rock triaxial compression and slurry permeating coupling process are carried out. The numerical simulation results veritably reflects the slurry permeability evolution laws in the broken process of rocks and fits the experimental data well.(4) Based on the engineering geological conditions of the deep bolt-grouting supporting roadway and using the developed slurry permeability evolution model of the fractured rock, the slurry permeability and diffusion mathematical model in the fractured roadway surrounding rocks is built, and systematic study has been made to analysis the effect of the roadway surrounding rocks fractured state, confining pressure, grouting pressure, grouting time and bolt-grouting drilling layout on the slurry diffusion range, which reveals the seepage and diffusion laws of slurry within fractured roadway surrounding rocks, and then a method to determine the optimum bolt-grouting time in the deep roadway surrounding rocks is put forward, which is conductive to providing a reference for bolt-grouting supporting practice in the deep roadway.