Research on experimental mechanism of grouting and interception of porous aggregate in coal mine

In China, coal mine water disasters occur frequently. Using slurry to block the porous aggregate in the roadway is an effective method to build a water blocking wall to achieve water closure. The on-site grouting process is difficult to control and observe. In order to better reveal the formation of grouting stone body, a set of visual grout aggregate penetration diffusion and plugging test device is designed to simulate the process of constructing water plugging wall by pouring porous aggregate under different working conditions. Under the orthogonal test, the inject ability of different aggregate size, slurry water cement ratio and roadway dip angle and the difficulty of plugging the roadway are studied, and the movement characteristics of slurry in porous aggregate are analyzed. The results show that in the process of hydrodynamic grouting, the deposition area first appears at the bottom of the roadway, then expands to both sides, and then develops upward until it fills the entire roadway; The effect of grouting closure is controlled by many factors. When the volume fraction of grout cement is 33% and the size range of aggregate is 1～2 mm, the downward roadway is easier to fill the aggregate gap; According to different flow states of grout in aggregate, the process of grouting closure can be divided into three stages: filling stage, sedimentation stage and pressurization stage; The essence of grouting closure is a process in which unstable cement particles in the grout are transformed into stone bodies through a series of physical and chemical reactions such as segregation, hydration, filtration, sedimentation, etc. in the filled aggregate voids to achieve water blocking. The research results have a reference value for the selection of river closure aggregate and slurry ratio, and provide a scientific reference for rapid plugging after water inrush in the roadway.