Simulation On Flowing And Diffusing Of Expansible Grouting Material In Cross Fractures

Grouting is an important means for seepage control and reinforcement of fractured rock mass and has been widely used in underground engineering.It is the premise of fine grouting to master the diffusion law of grout in rock mass fractures.As one of the important means to study the grout diffusion mechanism,numerical simulation has the characteristics of strong applicability and dynamic display of the grout diffusion process,and has been widely used.In recent years,based on the Computational Fluid Dynamics Theory,the grout diffusion process is regarded as a multiphase flow,The refined simulation study considering grout-gas or grout-water displacement has been paid more and more attention,and has obtained the relatively abundant achievement,but more focused on single fracture grouting simulation,in view of the grout flow in fracture network simulation research of diffusion process is relatively scarce.Based on this background,this paper carried out the research on the simulation method of the flow and diffusion of self-expanding grout in the cross-fracture.The main work carried out is as follows:(1)The basic principle of the quasi three-dimensional simulation model of grouting for flat fracture was analyzed.Based on the Hele-Shaw basic hypothesis,the calculation expression of diffusion conduction number at the fracture wall was derived,and the formula was applied to the momentum equation discretization.The threedimensional problem of grouting for flat fracture was transformed into a twodimensional problem considering the influence of fracture opening.The complexity of modeling and solving of fracture grouting flow field is significantly reduced.(2)The cross-fracture grid system was constructed.According to the change law of velocity and pressure when the polymer grout flowed through the cross interface,the cross boundary conditions of u velocity,v velocity and pressure were introduced.According to the distribution law of each physical quantity on the control volume near the cross interface,different interpolation methods were established,and the expressions of u velocity,v velocity and pressure on the cross interface were deduced respectively.The momentum discrete equation and the pressure correction equation at the intersection boundary were derived respectively by coupling the velocity and pressure of the three single fracture surfaces according to the cross boundary conditions.(3)based on the cross border the momentum of the discrete equation and pressure correction equation,using planar fissure grouting quasi three dimensional model to discrete fracture surface with SIMPLE algorithm iterative process of control,track the Youngs method in serous movement interface,realized the grout in the cross-fracture expansion flow numerical diffusion process,research and development of the corresponding simulation program.(4)The simulation program developed is used to simulate and calculate the process of polymer expansion and diffusion in cross-fracture under typical working conditions.The simulation results dynamically show the change rules of grout pressure field,velocity field and diffusion morphology with time under different initial grout filling states and different fracture boundaries.The pressure distribution characteristics of each fracture plane near the cross boundary and the variation of the flow direction and diffusion rate of the grout after passing the cross boundary are analyzed.Based on the quasi-three-dimensional simulation model of plane fracture grouting,a simulation method for the flow and diffusion of self-expanding grout in cross-fracture is established,which lays a foundation for the further study of the diffusion mechanism of polymer grout in fractured rock mass.