Grouting test and reinforcement mechanism analysis of rock with single penetrated fracture surface

Abstract

For the problem that how the grouting reinforcement of a single penetrated structural plane affects the bearing capacity of surrounding rock, an approach of rock samples preparation with single penetrated fracture surface is proposed firstly, and the rock samples are injected with ultrafine cement and epoxy resin, respectively. Then, the strength and deformation characteristics of the consolidated body under uniaxial (triaxial) compression are investigated with the RMT-150C experimental system. Finally, the micro consolidation mechanism of structural plane grouting is revealed using theoretical analysis and electron microscope scanning. It is found that the fracture surface generated under the triaxial loading-unloading condition is closer to the engineering practice and meets the experimental requirements. The stress−strain characteristic curves of the specimens injected with ultrafine cement show phased deformation characteristics, and the curves of the specimens injected with epoxy resin are relatively smooth. For the strength characteristics, the influence of confining pressure is significantly larger than that of grouting material selection. Grouting reinforcement can improve the residual strength of rock mass. With the increase of confining pressure, the increase of improvement coefficient of residual strength is less obvious, and the peak strength of the consolidated body is closer to that of intact rock. For the failure characteristics, the main fracture surface of the specimen injected with ultrafine cement shears and slips along the original fracture surface, and the main fracture surface of the specimen injected with epoxy resin is a new penetrated fracture surface. Finally, based on the Mohr-Coulomb criterion, the relationship between the bonding force of grouting materials and the strength improvement coefficient of structural plane is established. It is found that the strength improvement coefficient of structural plane has a linear relationship with the bonding force of grout. The comparison between the calculation and test results shows that the formula is reasonable and can provide a reference for the optimization of deep surrounding rock support.

Keywords

• structural plane
• grouting materials
• strength
• failure characteristics
• reinforcement mechanism