采场底板围岩应力壳力学特征及时空演化

针对采场底板围岩三维应力场特征及演化规律,以谢桥煤矿1232(1)综采工作面为研究对象,采用综合研究方法开展了系统研究。结果表明:煤层回采过程中,伴随着采场围岩三维应力场的不断调整,在采场底板围岩空间区域也存在高应力束,高应力束在三维空间形成了采场底板围岩应力壳,应力壳壳体内外岩体主应力均低于壳体中的主应力。应力壳内边界之上垂直应力和水平应力均显著降低,部分岩层内压应力转化为拉应力,壳体和应力壳外边界岩层垂直应力降低,水平应力仍然较大,存在水平应力集中现象,三维应力场作用的选择性是采场底板围岩应力壳形成的内在力学本质。采场底板围岩应力壳形态随着采场结构的变化而调整,具有典型的短边依赖效应,破裂区和最大位移区主要发育在应力壳壳体内边界之上的低应力区内。采场底板围岩应力壳是抵抗底板岩层卸压膨胀、进而发展到拉剪破坏的主要集中力系,采场底板围岩应力壳的失衡可能引起较大的动力现象。

Mechanical characteristics and time and space evolvement of stress shell in stope floor stratum

Selecting 1232(1) working face in Xieqiao Coal Mine as the research object,by employing of numerical simulation,physical modeling and in-situ measurement,the mechanical characteristics and time and space evolvement of stress shell in stope floor stratum were studied.The results show that there is high stress bunch in the floor stratum,and high stress bunch high forms the stress shell.The principal stress inside and outside the stress shell are lower than in the stress shell.The vertical stress and horizontal stress will decrease from above to below over the inner boundary of stress shell,and compressive stress become to tensile stress in local area.Meanwhile,the degree of horizontal stress relief is lower,and there are horizontal stress concentration areas in stress shell and outer boundary of stress shell.The selectivity of three dimensional stresses is the intrinsic mechanics essence forming the stress shell in stope floor stratum.The form of stress shell will adjust with the change of stope structure.The short side of working face length and forward distance affects the depth of stress shell.The destroyed area and maximal displacement region are in the low stress areas above the internal boundary of stress shell.The stress shell is the principal concentrated force system to prevent the rock deformation and damage.If the stress shell in stope floor stratum loses balance,high dynamic phenomena will happen.