Grouting sealing mechanism of water gushing in karst pipelines and engineering application

For the sealing problem of water gushing in karst pipelines, the sealing mechanism and method are investigated by numerical simulation, laboratory experiment and engineering application. The process of flow-control speed-down in large-flow and high-speed karst pipeline is simulated, and the change laws of flow velocity in the pipeline are analyzed. The modified construction solid waste cement-water glass grouting material is developed for plugging the water gushing in karst pipelines. The grouting sealing effect under different flow-control conditions is analyzed by grouting sealing tests. The results show that: (i) The flow velocity in the pipeline is effectively reduced by the flow-control speed-down. The greater the degree of flow-control, the more obvious the effect of speed-down. (ii) When the proportion of the modified construction solid waste cement-water glass grouting material in liquid a and liquid b is 1:1 and the mixing amount of waste red brick powder is 40–60%, the grouting sealing performance is the best. (iii) The slurry retention rate can be increased by the flow-control speed-down of dynamic water in the pipeline. The primary and secondary relationship of various factors affecting the grouting sealing effect is as follows: grouting quantity > initial flow velocity of the dynamic water > slurry type > water cement ratio > pipeline curvature. Research results are successfully applied to the water gushing treatment project of China Resources Cement (Pingnan) Riverview Limestone Mine, which have certain reference significance for the treatment of karst water gushing.