含瓦斯煤岩体采动致裂特性及其对卸压变形的影响

为了研究瓦斯压力对采动煤岩体卸压变形的影响，在FLAC平台上采用应变软化本构关系和“先加载后卸压”的方式，研究了不同瓦斯压力及围压条件下采动煤岩体的卸压致裂特性及其对卸压变形的影响。模拟结果表明：煤岩损伤破坏应力的峰值及所对应的轴向应变、应力峰后下降幅度随瓦斯压力的增加而减小，其力学特征由脆性逐渐向塑性过渡；瓦斯压力的增加使煤岩承载能力下降，并由于在有效应力空间中应力水平的提高而使拉伸破坏提前发生；随着瓦斯压力的升高，上覆煤岩采动煤岩卸压变形量、致裂破坏区不断增大，致裂特征更加明显，采动卸压范围、应力集中峰值及其距煤柱边界的距离也增大。因此，当煤层瓦斯压力较高时，瓦斯压力对采动煤岩体卸压变形的影响不能忽略。

Characteristics of depressurized fissure and its effect on deformation induced pressure relief of mining coal mass containing gas

The characteristics of fissure induced pressure relief at different gas pressures and its effect on deformation induced press relief of mining coal mass containing gas were analyzed by using FLAC software.A strain softening constitutive relation was used and the confining pressure was unloaded after the model reaching a static equilibrium state.The numerical results show that the peak stress and its corresponding axial strain of damage failure and the descend amplitude after peak stress decrease，with the rising gas pressure，and the mechanical characteristics become brittle from plastic.The supporting capacity of coal mass containing gas decreases with the rising gas pressure，and the tensile failure appeared ahead caused by increasing stress in effective stress space.The depressurized deformation and failure area induced pressure relief are larger with higher the gas pressures at the same confining pressure，and the characteristics of fissure induced pressure relief are more obvious，which caused the peak stress rising and its location away from the pillar longer.When the gas pressure reaches a certain value，the effect of gas pressures on the depressurized deformation of mining coal mass containing gas cannot be neglected.