厚煤层大采高采场煤壁的破坏规律与失稳机理

Breakage and falling of a high coal wall in a thick mined seam

基于大采高采场煤壁稳定性控制需要,在现场实测基础上,采用数值模拟分析了煤层采动裂隙的发展演化规律,并用滑移线理论分析了煤壁失稳的力学过程.研究表明:仅含层理煤层的采动剪切破坏面由倾向相反的共轭面组成;含节理煤层中,硬煤的采动破坏面为剪切破坏面与节理张裂面组成的倾向相反的共轭面,软煤采动破坏面为倾向采空区的单向平面;超前塑性区内硬煤的后继剪切破坏面仍为倾向相反的共轭面,软煤内则为倾向煤壁的单向平面.采用塑性滑移线确定了煤壁片帮的危险范围,影响煤壁失稳的主要因素为端面距与砌体梁结构的回转变形压力.

Field measurements and simulations of the evolution and appearance of mining in- duced fracture are used to explain the development of rip falls. The mechanics behind these falls is discussed. Results show that a coal seam with bedding only has a mining induced frac- ture plane consisting of two conjugate planes with an inverse incline. Jointed coal seams have a fracture plane consisting of a sheared crack plane and an open plane in the joints. These have an inverse incline in hard coal, relative to the goaf, but one set shear plane inclining to the goaf in soft coal. Slip-line theory can identify the danger zone by the coal wall. The main factor that induces instability in the wall is the unsupported roof length of the tip-face and the pressure on the voussoir beam.