考虑爆破瞬态卸荷的深部岩巷损伤范围研究

Study on Damage Zone of Deep Rock Tunnel Considering Transient Blasting Unloading Effect

为了研究深部岩石巷道爆破瞬态卸荷的损伤效应,本文采用弹性动力学方法,利用Laplace变换和留数定理求解了深部岩巷爆破卸荷瞬态应力场的动态解析解,结合拉伸损伤和剪切损伤的阀值条件,给出了损伤破坏区的范围和损伤程度,并探究了损伤区分布的影响因素。算例表明,围岩以拉伸损伤破坏为主,岩石的脆性越强,损伤变量越大。爆炸荷载越大,拉伸和剪切损伤破坏区范围越大;原岩应力越高,拉伸损伤破坏区越小,剪切损伤破坏区越大,原岩应力对拉伸损伤效应有显著的"抑制"作用。当岩石单轴抗拉强度较小、内聚力较大时,围岩只存在拉伸损伤区不存在剪切损伤区;当岩石单轴抗拉强度较大、内聚力较小时,围岩既存在拉伸损伤区又存在剪切损伤区。

In order to investigate the transient blasting unloading effect in deep rock tunnel. The Elastic Dynamics Method,Laplace transform and residue theorem are used to solve the dynamics analytical solutions of stress field under transient blasting unloading around the deep rock roadway. Combined with the tensile and shear damage threshold condition,the damage failure zone and the damage degree of the blasting transient unloading of the deep rock tunnel are given,and the factors impacting on distribution of damage zone are discussed. The example shows that the surrounding rock failure zones induced by transient blasting unloading are mainly composed of tensile failure. For the same conditions,the more brittle the rock is,the larger the damage value will be. The bigger the blasting load is,the bigger the tensile and shear damage failure zone will be. With the in-situ stress increasing,the tensile damage failure zone decreases,but the shear damage failure zone increases. The tensile damage effect is obviously inhibited by the in-situ stress in surrounding rock. For big uniaxial tensile strength and small cohesion,the damage failure zones just includes tensile damage zones and without shear damage zones. Conversely,for small uniaxial tensile strength and big cohesion,the damage failure zone includes both tensile damage zones and shear damage zones.