Mechanism and prevention technology of water inrush and sand inrush occurred in thawing process of mine freezing shaft wall

In order to solve a water inrush and running sand problems occurred in the thawing process of the freezing shaft wall in the watery sand layer, with the theoretical analysis, indoor test and site test, a study was conducted on the formation mechanism of the water inrush and running sand occurred in the thawing process of the freezing shaft wall in the watery sand layer, the grout setting features under the low temperature environment and the technology and method of the grouting and water dispersed as well as the sand consolidation. The study results showed that during the thawing process, the water permeable channel would be the construction cold joints and the concrete shrinkage cracks. The water inflow would be increased with the thawing scope expanded, the cracks also would be expanded and finally a disaster of the water inrush and running sand would be caused. A grouting with a sleeve valve pipe could effectively backfill the cracks around the mine shaft liner, could disperse the underground water and could consolidate the sand. With the grout mixed with 5 % industrial salt, the mud slurry setting time would be obviously shortened and the compressive strength and bending strength both would obviously increased. After the grouting completed, the water inflow in the mine shaft was decreased from 400 m3/h to 70 m3/h and reached the targets to seal the channel, reduce the material sources and decrease the water head.