Modification and control technology for shallow-buried and highly-weathered fractured roofs in one fully mechanized mining face

LIU Guoqing; LIANG Ming; WU Gang; HU Haodong; WANG Qiang; QIAO Yiyang; LIANG Shun

doi:10.11799/ce202601009

Abstract：To address the challenges of roof management under the coupled conditions of shallow burial,intense weathering,fractured roof,and valley landforms,we focused on the roof control of 3209 working face in Fengjiata Coal Mine as it traversed a highly weathered zone.Using field measurements,numerical simulation,theoretical analysis,and industrial testing,the stability control technology for surrounding rock throughout the excavation and mining cycle in the shallow weathered zone of the 3209 working face was investigated.The reinforcement effect of grouting cables on the roof during roadway development was evaluated,and the mine pressure behavior mechanism under the coupling effect of surface valley topography and roof weathering in shallow mining faces was revealed.The results indicate that during panel extraction,the maximum vertical stress in the haulage roadway roof reached 2.45 MPa,the maximum roof subsidence was 248 mm,the maximum extent of the plastic zone was approximately 20 m,and the cracks in the roof were predominantly tensile-shear fractures.Under the ravine landform,the maximum surface subsidence above the working face was 1.76 m,the peak front abutment pressure was 5.40 MPa with a stress concentration factor of 1.8.After the mining distance exceeded 80 m,crack development tended to stabilize.A control technical scheme involving grouting"reconstruction"for the highly weathered and fractured roof was proposed to ensure safe mining.Field implementation showed that roof grouting effectively enhanced the overall stability and deformation resistance of the surrounding rock.During the working face extraction,only localized rib spalling and face fall occurred,and the working face advanced smoothly without shield support failure.This effectively resolved the surrounding rock control challenges throughout the excavation and mining cycle in the shallow weathered zone.