Study on instability mechanism and control technology of support in erosion working face with erosion zone

Affected by the erosion of scouring zone, the third panel of Baode Coal Mine 8^# coal seam has a large area of roof hanging, which threatens the production safety of the working face.In order to solve the significant problem of ground pressure in the eroded working face in the scouring zone of 81308 working face and ensure the safe and efficient mining of coal seams in the eroded area of the scouring zone, by establishing the overburden structure model of the eroded coal seam stope in the scouring zone, the instability mechanism of roof surrounding rock and the bearing characteristics of support are studied, and the hydraulic fracturing roof weakening measures are put forward.The results show that the pressure step of roof increases under the erosion of scouring zone.After the scour body breaks and collapses, the filling degree of the goaf is high, so that the rotary subsidence of the key layer can form a stable masonry beam structure, and the support is in a given deformation state.During the pressure period, the overburden load borne by the support is slightly greater than the rated working resistance.In order to avoid the pressure accident, hydraulic fracturing measures should be taken to weaken the roof.The support load monitoring data show that after the roof is weakened by hydraulic fracturing, the initial pressure step of the basic roof is 28 m, the periodic pressure step is 20 m, and the pressure is relatively stable.Only a small number of supports have safety valves opened, indicating that the roof weakening measures have achieved good results.This study provides guidance and reference for Baode Coal Mine and similar mines.