Abstract: To address the drawbacks of traditional dynamic water grouting materials, such as long gelation time, low dynamic water retention rate, high cost, as well as the problem of ineffective utilization of industrial solid waste fly ash in power plants under the “coal electricity integration” business model. Based on the demand for water blocking treatment in coal mine water rich sand layers, orthogonal experiments were conducted on cement-fly ash-water glass grouting materials using slurry water-cement ratio, fly ash content, bentonite content, and retarder content as experimental factors, and slurry apparent viscosity, water separation rate, gelation time, and dynamic water retention rate as indicators. The optimal slurry ratio that meets the engineering requirements was selected through range analysis and comprehensive balance analysis. Based on the optimal slurry ratio, a simulation experiment was conducted on the water blocking effect of dynamic water grouting materials. The effects of grouting pressure and grouting volume on the water blocking performance and diffusion ability of slurry were analyzed, and the water blocking effect of optimal slurry under dynamic water conditions was verified. The results show that the optimal slurry ratio is water-cement ratio of 1.2, fly ash content of 30% (mass fraction), bentonite content of 6% (mass fraction), retarder content of 1.75% (mass fraction), and water glass content of 5% (mass fraction). The effective diffusion distance of optimal slurry shows a positive correlation with grouting volume. As the grouting volume increases, the diffusion capacity of slurry enhances while slurry loss decreases. When the grouting pressure is not less than 40 kPa and the grouting volume is not less than 800 mL, the average water blocking rate of grouting materials under optimal slurry ratio exceeds 90%, demonstrating excellent water blocking effect.

Key words: fly ash, grouting water blocking material, orthogonal experiment, dynamic water retention rate, water blocking rate