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隧洞毫秒爆破开挖推进过程中,预留岩体在重复爆炸荷载作用下产生不可逆的损伤叠加。而现有的岩体爆破损伤数值模拟基本都是针对单孔装药和单段爆破,很少涉及实际工程中的重复爆炸。基于LS-DYNA程序的用户自定义材料接口,将统计损伤演化模型嵌入到弹塑性本构材料中,模拟圆形隧洞全断面毫秒爆破过程中重复爆炸荷载作用下的岩体累积损伤效应,并考虑地应力对岩体爆破损伤的影响。计算结果表明,围岩损伤范围和损伤程度随重复爆炸荷载次数而增加,在一个爆破进尺内,围岩损伤的临界峰值质点振动速度较单段爆破降低了12%;爆炸荷载作用下,围岩主要表现为拉损伤,围岩地应力对爆破张拉效应起到非常敏感的“抑制”作用,在2~10 MPa应力水平时,围岩爆破累积损伤范围随着应力增加而明显减小,围岩损伤的临界峰值质点振动速度增加24%~57%。
Millisecond blasting excavation tunneling process, reserve rock mass in the repeated blasting load irreversible damage superimposed. However, the existing numerical simulation of blasting damage in rock masses is mainly directed to single-hole charge and single-stage blasting, and few involve repeated explosions in practical engineering. Based on the user-defined material interface of LS-DYNA program, the statistical damage evolution model is embedded into the elastic-plastic constitutive material to simulate the cumulative damage effect of rock masses under repeated blast loads during the full-scale millisecond blasting of circular tunnels Influence of Ground Stress on Blasting Damage of Rock Mass. The calculation results show that the damage range and damage extent of surrounding rock increase with the number of repeated blasting loads. Within one blasting footage, the critical peak vibration velocity of surrounding rock damage is reduced by 12% compared with single-stage blasting. Under the explosive load, Mainly for tensile damage, the surrounding rock stress is very sensitive to “blasting” effect of blasting. At the stress level of 2 ~ 10 MPa, the cumulative damage range of surrounding rock blasting decreases obviously with increasing stress , The critical peak particle vibration velocity of surrounding rock increased by 24% -57%.