Research on visualization detection method of overlying strata three zones in thin coal seam mining

Abstract

The mining of thin coal seam resources is seriously affected by the overlying coal seam gas. The detection of three zones of goaf roof is of great significance to the safety production. In this paper, we carried out loading coal and rock resistivity testing experiment, analyzed the loading damage in the process of coal and rock resistivity change and distribution, and carried on the theoretical analysis and numerical simulation of overlying strata three zones according to the actual embedded depth, and then carried out field test. Direct current method has been used to test the forward three-zone apparent resistivity distribution. The main conclusions are as follows: the resistivity changes due to the crack propagation of coal samples, and the resistivity surge point corresponds well with the failure point of coal and rock; in the process of coal and rock failure under load, there are abnormal areas in the resistivity cloud diagram under load, and it migrates with the uneven deformation of coal and rock under load; the collective subsidence of the goaf after the roof is cut in the coal seam mining will form a large sectioned area in thefracture area of the upper part of the goaf. There are large cracks in this part of the sectioned area, and it will extend to the roof rock of the return air roadway, resulting in the increase of cracks in the rock; the electrical detection results show that the horizontal distance from the working face to the caving zone is about 20 m, and the influence resistance value of the fracture zone becomes larger and its height is 17 m, which is consistent with the theoretical calculation and numerical simulation results.

Keywords

• thin coal seam mining
• overlying strata three zones
• electrical test
• visual detection
• numerical simulation