Development and application of simulation test system for confined water conduction in fault zone

Currently, there is no effective monitoring method to collect the data of confined hydraulic conductivity rise in fault zone in similar material test. Therefore, it is not systematic to study the law of activated water inrush of fault only from the perspective of stress change and fracture propagation. To study the activation characteristics of fault zone and the influence of grouting technology on the water inrush behavior of faults in the course of longwall face advancing, this paper takes the geological data of the Xinyuan Coal Mine as the background. Two-dimensional similar material test platform and self-made confined water conduction system were used to study the stress evolution law, fracture development law and confined water conduction characteristics of the fault zone and adjacent strata before and after grouting in the course of longwall face advancing. Systematic research had been carried out. The results show that the confined water conduction system not only characterizes the mechanical effect of aquifer on the rock mass in the floor, but also realizes the continuous acquisition of water conduction height data during mining process. In the process of the longwall face advancing, floor rock mass will undergo three basic stages: pre-mining compression, post-mining expansion and stress recovery. The ‘barrier’,effect of fault zone will cause stress concentration occurring in the bottom of its adjacent area and expansion of the damaging area. With the decreasing of the waterproof coal pillar size, the disturbance of mining stress on fault zone and slate limestone aquifer becomes more obvious. When the coal pillar size is reduced to less than 30 cm, the amount of strata separating from the lower wall of fault zone increases sharply, and the cracks previously blocked by grout in Pansan limestone-limestone aquifer opened again. The height is closely related to the size and width of the coal pillar. The grouting technology effectively ensures that the flow height of the coal pillar maintained at 9.6 cm in the process of reducing the size of the coal pillar from 36 cm to 30 cm. However, when the longwall face advances on the basis of the width of the coal pillar at 30 cm, the height of the confined water in the fault zone will increase rapidly.