Experimental Study on Grouting Reinforcement Mechanism of Heterogeneous Fractured Rock and Soil Mass

Abstract

To explore the grouting reinforcement mechanism of heterogeneous rock and soil in a fault fracture zone, based on the F2 fault grouting project of Yonglian Tunnel, the filling area composed of loose and soft media in the fault is defined as the advantageous grouting diffusion region, which is divided into loose and weak diffusion regions according to the slurry diffusion form. A self-developed grouting reinforcement test system is used to carry out grouting reinforcement tests on the heterogeneous rock and soil. The existence of the advantageous diffusion region can effectively improve the reinforced body strength. The slurry in the reinforced body containing the loose medium mainly expands outwards in the form of first infiltration and then compaction, and the slurry vein mainly remains in the advantageous diffusion region. The slurry in the reinforced body containing the soft medium mainly diffuses in the form of compaction splitting, which can form thicker splitting of the grouting veins. When the reinforced body is destroyed, the body containing the loose medium is mostly conically fractured, indicating complete lithology and homogeneous material. Moreover, the reinforced body containing the soft medium always forms a penetrating crack along the slurry vein or near the grouting vein. Focusing on the heterogeneous stratum consisting of fault breccia and soft plastic fault gouge, controllable slurry dynamic adjustment, same-hole multi-sequence sub-gradient grouting, and localized grouting control are proposed. The grouting control method is applied to the case of Yonglian Tunnel, and a superior grouting reinforcement effect is achieved.