Research and application of water displacement and sand consolidation grouting technology for treatment of loose water-bearing sand layers in thin bedrock

WU Yanjun; DU Botao; SHI Yongli

doi:10.11799/ce202601007

Abstract：To address the critical challenge of water and sand inrush from loose layers in coal seam roof areas with thin bedrock,we systematically analyzed the four essential conditions for such disasters:water-sand source,transport pathways,driving forces,and accommodation space.Accordingly,a water displacement and sand consolidation grouting treatment technology was proposed.Its core principle involves reconstructing the hydrodynamic field of the loose layer through high-pressure grouting to form a spatially interconnected"root skeleton"network that extends vertically and interlocks horizontally.This achieves the dual objectives of displacing water from the loose sand layer and reinforcing stratum stability.Based on this concept,targeted drilling type selection criteria and key parameters were established for different hydrogeological conditions.The applicability of four grouting modes—Flat-Pushing,Central Blooming,Cap Covering,and Edge Locking—was clarified,along with the key supporting parameters such as grouting materials,pressure,and volume.According to the field application at Wugou Coal Mine,after treatment,the maximum specific yield of the sand layer in the Quaternary aquifer decreased to 0.000474 L/(s·m),and the grouting pressure in inspection holes increased by 15.3%～57%compared to pre-treatment levels.Multi-dimensional data,including characteristics of grout return via inter-hole communication,monitoring of grout diffusion distance,and borehole core sampling results,collectively confirmed the effective formation of the"root skeleton"grout diffusion network.This significantly reduces the risk of water-sand inrush disasters,providing a systematic solution integrating concept,technology,and parameters for preventing and controlling water hazards in loose layers within coal seam thin bedrock zones.