Study On Grouting Diffusion And Reinforcement Mechanism Of Single Fracture

The stability of rock mass is significantly influenced by the property of structure surface. The mechanical property of rock is determined by the distribution, the combination characteristics and construction property of structure surface. Water disasters induced by structure surface severely influence the construction and operation safety of underground project, which causes great casualties and economic losses. Thus, the fractured rock grouting and reinforcement mechanism has become an important issue during underground construction in our country. In this study, the fractured rock grouting and reinforcement mechanism is studied using theoretic analysis and numerical simulation, and a series of useful results is achieved.(1) Geometrical model of structure surface was constructed using fractional Brownian function. Finite element analysis on fracture grouting process was carried out based on N-S equations. The influence of the roughness and connectivity of joint surface was analyzed, and the rationality of modified cubic law was investigated. The rock and grouting coupling effect during grouting process was analyzed based on interface layer theory. Based on the modified cubic law, the constitutive interface layer equation and grout motivation equation, a grout spreading equation was proposed with consideration of joint surface roughness and rock and grout coupling effect.(2) Based on neural network algorithm, a calculation model was constructed for joint surface roughness. Using PSO and BP combining algorithm, the search capability was optimized and the accuracy was improved. With three dimensional joint surface discrete, the two dimensional model was generalized to three dimensional situation.(3) In order to solve the problem of grouting reinforcement on single structural surface, the shearing failure mechanism and the coupling effect cohesion and friction force was investigated. The characterization methods for joint surface roughness anisotropy were analyzed. The idea for cohesion and friction force controlling area division was proposed. Grouting reinforcement body shearing strength calculation formula was proposed, which provides evaluation methods for rock mass grouting effect.(4) Based on discrete element particle flow code, the structural surface property and cohesion effect was characterized with SJ model, and a numerical model of structural surface shearing strength was constructed. The shearing strength of single saw-toothed surface and the typical JRC surface was numerically studied. The shearing characteristic and failure mode was analyzed and the cohesion and friction force coupling effect was studied. The influence on structural surface shearing property from the cohesion force and the grouting reinforcement mechanism was revealed.