High-pressure jet disturbance grouting technology for water and sand inrush in roadway tunneling and its application

In order to control the water and sand inrush in roadway tunneling under weak consolidated formation conditions, taking water and sand inrush during the No.2 coal seam roadway tunneling in Maiduoshan Coal Mine of Ningdong Coalfield as the research object, the problems of large amount of engineering, long period of surface treatment and high risk of underground treatment were solved. The construction of the blocking body at the water and sand inrush point was completed by using the water-retaining wall construction technology, high-pressure jet disturbance grouting technology, the integration of drilling and grouting technology, and the pressure control and slurry retention technology. The results show that the flooded area of water and sand can be controlled effectively by constructing the water-retaining wall in the roadway during grouting. With the strength of the water-retaining wall and surrounding rock being calculated, the water-retaining wall can resist at least 1.64 MPa of pressure, which is greater than the water pressure of the roof aquifer (1.2 MPa). Firstly, the No.1 blocking body was constructed by high-pressure jet disturbance grouting in the area far from the water and sand inrush point to reduce the submerged range. Then, the No.2 blocking body was constructed in the area close to the water and sand inrush point to control the surrounding area. The development of integrated drilling and grouting technology and its relevant equipment can avoid borehole collapse after drilling, which affects subsequent grouting, and achieve continuous drilling and grouting operation. The orifice pressure control and slurry retention device was invented for the efficient use of grouting under the pressure of 20 MPa. The quality of the blocking body formed by the consolidation of loose sand in the roadway was tested by the coring and water injecting test. The coring was complete and the blocking body was watertight under 1.8 MPa water pressure, indicating that the block body has a good quality. The use of high-pressure jet disturbance grouting to control water and sand inrush in the roadway is safe, efficient and economical, and can avoid the occurrence of secondary disasters during treatment effectively.