Mechanism of mine pressure behavior and roof control technology in fully mechanized working face crossing district concentrated coal pillars

LUO Wen; JIA Shiyao

doi:10.11799/ce202312017

Abstract：Taking the complex mining conditions of Shendong mining area as the research object,and the special rules of mining pressure behavior under the goaf and district coal pillars were studied.The static load model and dynamic load model of the mining face under the coal pillars of the section were constructed.The stress calculation method of the upper coal and lower coal was derived in the static load model.In the dynamic load model,the additional load caused by the collapse of the main roof rock block of the upper coal due to the mining damage and coal pillar instability was calculated,and the influence of entering and leaving the district coal pillar on the hydraulic support force was analyzed.Based on the geological and mining conditions of the working face of Halagou Coal Mine in Shendong,a numerical model was established to simulate the variation law of the coal roof pressure when the mining face was entering and exiting the coal pillars.By analyzing the monitoring data of the roof stress 5～10 m in front of the coal wall,the conclusion was drawn that the stress increase of the out-coal pillar was more than 10%higher than that of the in-coal pillar.This conclusion not only verifies the rationality of the dynamic load model derivation but also provides a basis for the selection of dynamic load coefficients for entering and exiting coal pillars.The B coal pillar area that the working face is about to pass through is treated with hydraulic fracturing and pressure relief measures to soften the rock layers and reduce pressure.The field measurement data shows that the resistance of the hydraulic support when entering and exiting the B coal pillar is reduced from 22333 kN in the A coal pillar area to 19616 kN,and the periodic weighting interval is reduced from 21.7 m to 18.28 m,effectively alleviating the influence of pressure changes in the entering and exiting district coal pillars on the hydraulic support state.