Study on Grouting Mechanism Based on GIN Method in the Rough Rock Fractures and Corresponding Effectiveness Assessment

The fracture zone in the mining areais taken as the research object,and the grouting strength value method (GIN method) is used to study the grouting reinforcement mechanism.Firstly,the GIN grouting model of rough fracture in rock mass was constructed based on the finite element software to verify the feasibility of the grouting model and the effectiveness of controlling the grouting process.Subsequently,focusing on the four main influencing factors in fracture zone grouting:fracture surface roughness,grouting rate,fracture aperture and fracture density,the intersection law of the grouting curve and the GIN curve,the changing law of the radius of grout diffusion,the grouting pressure,and the grout injection degree are studied in depth,and the termination indexes of the grouting under the different influencing factors of the GIN method are put forward.On this basis,taking the fracture zone in a mining area as the research object,a GIN grouting model considering the actual occurrence characteristics of the fracture zone was constructed,and the relationship between the grouting curve and GIN curve,the degree of injection,the change law of the grouting pressure and the grouting radius during the grouting process of the fracture zone was studied.The following results were obtained:The GIN method is more compatible with grouted sections with different fracture apertures and fracture densities,but this compatibility decreases as the radius of the grouting design increases.The GIN method is more suitable for low and medium speed grouting processes.When the sum of the apertures of multiple fractures per unit height is small (<3mm),it can be equated to a single fracture with the same sum of apertures,but when the sum of the apertures is large,it can no longer be equated to a single fracture to study the effect of the grouting.When a fixed GIN value is used to control fractures with different apertures in the same grouting section,it is possible to ensure that fractures with different apertures can be filled and compacted by reducing the height of a single grouting section or by grouting fractures with different apertures in separate batches.