Inorganic Cement Grouting for Reinforcing Triangular Zone of Highly Gassy Coal Face with Large Mining Height

Abstract

Aiming to address the serious problem of coal wall spalling in the triangular zone of the coal face end under high-intensity mining, this paper introduces inorganic cement grouting reinforcement technology for medium-depth holes based on the specific geological conditions of the Sihe coal mine in China. Firstly, the effects of different water-to-material ratios and various accelerators on setting time and uniaxial compressive strength (UCS) of grouting materials and consolidation coal are studied. The results show that the combination of 2% accelerator I, 0.3% accelerator II, and 3.0% accelerator III was the most effective. Then, FLAC3D numerical simulation software was used to analyze the distribution laws of the plastic zone, the lateral abutment pressure, and abutment stresses in the face ends during repeated mining. The results indicate that the zone within 25–65 m of the front of the coal face was initially affected by the front abutment pressure. In this area, the stress value decreased slowly and fracture development was relatively intense. Grouting with high pressure and a large flow rate should be used in this scenario as the industrial experiment results indicated that the proposed inorganic cement grouting reinforcement technology could effectively control coal wall spalling and provide technical support for safe and efficient mining.