Diffusion mechanism of splitting grouting in deep buried soft rock based on time-varying grout viscosity

Abstract

To address the fact that the mechanism of split grouting in deep weak rock formations lags far behind engineering practice, this study develops a theoretical model for splitting diffusion in a single fracture by integrating the fracture propagation morphology and slurry flow behavior. Using coupled theoretical equations within the numerical simulation software, a numerical model of grouting-induced splitting in weak rock formations was developed considering the rheological properties of the slurry viscosity. Based on the numerical simulations investigating the effects of the formation depth, slurry viscosity, and grouting rate on the effectiveness of split grouting diffusion, during split grouting operations in deep rock formations, a relatively high initial grouting rate and pressure is recommended to be adopted in the early stage to initiate or connect fractures. Following grouting pressure stabilization, the slurry viscosity should be appropriately increased to promote rapid gelation along the fracture surfaces, thereby effectively sealing the fractures. A grouting control strategy featuring initial high-pressure, high-flow injection followed by low-rate consolidation was systematically developed and successfully applied to the reinforcement of fractured surrounding rock in the −1000 m floor slab of the vehicle yard roadway in the eastern section of Guqiao Mine, achieving notable engineering results.

Keywords

Deep mining / Split grouting / Formation depth / Slurry viscosity / Grouting rate / Grouting pressure

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