Mechanism and control of asymmetric floor heave in gob-side entry under dynamic pressure in ultra-thick coal seams

ZHANG Qi

doi:10.11799/ce202502007

Abstract：In order to control the asymmetric damage of the floor in the gob-side roadway under dynamic pressure due to tense mining-excavation arrangement,on-site research,theoretical analysis,numerical simulation and on-site industrialized test were conducted taking the 5209 air-return roadway as the object of research,and the formula was derived by the mechanical analysis to calculate vertical stress on both sides of roadway during the roadway excavation period and after the upper face mining.The mechanism of asymmetric floor heave in roadway was elucidated through numerical simulation.The results showed that the stress superposition caused by excavation and working face mining was manifested as the stress on the coal pillar side of the roadway being greater than that on the solid coal side,and the asymmetric distribution of stress has caused asymmetric deformation of the roadway floor.The displacement curve of the roadway floor by numerical simulation during roadway excavation shows a symmetrical distribution,with a maximum displacement of 29 mm.The deformation of the floor during upper working face mining is asymmetric.The displacement of the left floor of the roadway is maximum at a distance of 0.5 m from the central axis,with a peak displacement of 593 mm.The plastic zone of roadway gradually expands during the upper working face mining,the depth of the floor failure is 5.5 m.According to the principle of collaborative control of roof,sides and floor,the cooperative control scheme of"floor leveling+anchor cable support+concrete hardening"was proposed and successfully applied in the field.