Simulation test of water and sand burst in shallow and thin bedrock face and analysis of influencing factors

Aiming at the problem of multiple water and sand disasters in the ancient gully area during the mining process of the first layer of coal resources in the Yushenfu Mining Area, the problem of shallow buried depth, thin bedrock, thick loose layer and water in the ancient gully area was explored. The water and sand burst disaster mechanism of the working face, the self-developed water and sand burst start tester was used to realize the indoor test simulation of the water burst and sand burst disaster process of the shallow buried and thin bedrock thick loose aquifer. According to the site characteristics of the water and sand disaster, six factors affecting the initiation of water and sand burst, including water head height, the fracture characteristics (fracture size and inclination), the thickness and compactness of the sand body, and the thickness of the clay layer. The design was based on the principle of orthogonal experiment, and 25 sets of water-sand burst start-up simulation tests were carried out. By summarizing the test characteristics of 25 series of experiments, the law of the process of disasters caused by water and sand disasters was obtained: water seepage - water volume increase - water mixing - water sand sand bursts. The degree of influence of different influencing factors on the initiation of water and sand disasters was quantitatively studied by using the range analysis method. It is found that the height of the head is the most important factor affecting the occurrence of water and sand disasters, and the influence degree is 37.5%. Furthermore, it is proposed that draining water before mining is an effective measure to reduce the occurrence of water and sand disasters. A comparative analysis of the hazards and disaster characteristics of water burst and sand burst disasters under different water head heights was made, and the mathematical relationship between the critical hydraulic slope initiation of the disaster and other influencing factors was obtained, which provides a basis for the research on the mechanism of water and sand burst disaster.. The experimental characteristics of the pore water pressure drop in the loose aquifer before the start of water and sand burst provides a basis for on-site disaster monitoring and early warning.