Grouting characteristic in rock fractures with different structural properties: Apparatus design and experimental study

Rock fracture surfaces are normally rough, with upper and lower surfaces presenting obvious structural properties (i.e., matching or mismatching). In this paper, rock fracture was divided into shear and tensile fractures based on its mechanical origin. A test simulation system for grouting in rough fracture (tensile and shear fractures) with continuous pressure field monitoring was proposed. A series of grouting simulation tests were employed to evaluate the effect of fracture structural property, fracture surface roughness, and aperture on the characteristics of grout flow in the rough fracture. The results show that grouting pressure exhibited a trend of rapid increase followed by a slow increase with time during the grouting in the tensile and shear fractures. Grouting pressure increases with time in a smooth relationship for tensile fracture and a fluctuating upward relationship for shear fracture. The slurry pressure distribution along the penetration length exhibited a nonlinear attenuation trend. The attenuation degree of the slurry pressure was positively related to the fracture roughness and the roughness difference in the upper–lower fracture surface and negative with the fracture aperture. The potential filtration effect during the grouting process is an important factor affecting the grouting behavior in the rough fracture.