Mechanism of rapid interception of flowing water in water-flowing roadways

Borehole-controlled grouting with grout-conserving bags can solve such technical problems as big work amount, long construction period and apt secondary disasters during interception of flowing water in traditional water-flowing roadways, and realize rapid emergency rescue and production recovery. In order to further study rapid construction mechanism of water-blocking wall, mechanism of rapid interception by borehole-controlled grouting with grout-conserving bags was studied through analysis of typical engineering cases and physical simulation tests of rapid interception of flowing water in water-flowing roadways. Results have shown that major controlling factors of rapid interception of flowing water by borehole-controlled grouting with grout-conserving bags include pressure of flowing water, flowing water amount, and mechanical strength of roadway surrounding rocks. The flowing water interception model with throwing grout-conserving bags plus supplementary grouting is only appropriate for water inrush interception environment of low flowing water pressure, small flowing water amount, and high mechanical strength of surrounding rocks, and its rapid interception mechanism is that small flow velocity between bags maintained by grout-conserving bags saves cement-sodium silicate dual grout from being attacked by flowing water during diffusion and condensation. Subsequent migration and diffusion of dual grout gel between bags can be controlled, and dual grout gel can quickly connect with roadway roof, which is conducive to rapid construction of water-blocking wall in interception roadway. In contrast, flowing water interception model with throwing grout-conserving bags plus pouring aggregate and supplementary grouting is appropriate for water inrush interception environment of high flowing water pressure, big flowing water amount and low mechanical strength of surrounding rocks. Its rapid interception mechanism works in three steps. Firstly, grout-conserving bags can complete part of aggregate pouring and filling stage in advance. Secondly, high-speed water flow environment at residual water-flowing section of grout-conserving bags can quickly discharge air carried into the roadway during aggregate pouring out of the roadway, reduce the number of hole pluggings during aggregate pouring, and speed up aggregate pouring rate. Finally, water-blocking body composed of grout-conserving bags and aggregate has water-blocking performance of high resistance and weak permeability, whose high resistance can make water-blocking body resist higher hydrodynamic pressure, reduce frequency of breakthrough and reconstruction of water-blocking body due to rapid pressure rise of water-blocking section during aggregate pouring, and low permeability can create favorable conditions for rapid condensation of supplementary grouting slurry in the later construction stage of water-blocking section. © 2021, Editorial Board of Journal of Mining & Safety Engineering. All right reserved.