损伤围岩中爆炸应力波动的数值模拟

应用有限元方法分析了硐室损伤围岩中爆炸应力波的传播和应力分布特征，通过引入JHC本构模型和岩石损伤变量D探讨了应力波作用下岩体的损伤演化模式。研究表明:围岩初始损伤对后续爆炸应力波的波动性质、作用范围和围岩应力分布具有不同程度的影响。当初始损伤超过某临界值后会显著地影响应力波的波动范围和围岩应力分布；在一定爆炸当量下，爆炸应力存在一个有效作用范围Lp，该范围塑性区以内，爆炸应力对岩体的损伤随围岩初始损伤增大而增大；有效作用范围Lp以外，围岩初始残余非弹性变形积累和单元残余拉应力可以平衡爆炸应力波动产生的损伤叠加效应，耗散了爆炸应力作用和波动能量。分析了产生在这种现象的原因。给出了有效作用范围Lp与围岩初始等效应力p之间的经验关系。

Numerical analyses of blast wave stress propagation and damage evolution in rock masses

By means of finite!element method the blast wave stress propagation and stress distribution in the wall rocks damaged by initial tunneling excavation were numerically analyzed.The damage evolution of rocks subjected to the wave stress was evaluated upon the employment of JHC constitutive model and damage variable D of rock element.It is shown that the influence of initial damage existing in wall rocks on properties of wave stress propagation,affecting domain and distribution depends on the extents of initial damage.The initially existing damage has apparently affected on wave stress propagation and stress distribution as long as its quantity exceeds a threshold value.It turns out that there exists an effective acting span Lp by which the blast wave stress influences on th initially damaged rock as long as a certain volume of explosive remains.Within this domain,the rock damage induced by blast wave stress increases with the increment of initial damage of rocks.Beyond this area scaled by Lp,the accumulated residual inelastic strains and residual tensile stresses in the damaged elements seem to be capable of balancing the compression wave stress resulted from the later explosion,and therefore,prevent the elements from being over damaged.This mechanism seems to dissipate the blast wave stress action and vibration energy.The reason for this phenomenon and mechanism was interpreted.In addition,the relationship between the effective acting span of wave stress and the initial damage in terms of equivalent stress was derived.