考虑岩体完整程度的岩石爆破损伤模型及应用

现有爆破损伤本构模型未能考虑岩体完整程度对爆破作用效果的影响。为此,对Yang等提出的爆破损伤模型进行了改进,建立考虑初始损伤的弹塑性爆破损伤本构模型及提出用于评价围岩受爆破影响的损伤判据。该本构模型包含初始损伤变量和岩体完整性指数、声波波速等参数间的关系式,并利用岩体初始完整性指数的变化考虑其完整程度对爆破损伤作用的影响。把该模型引入到LS-DYNA数值软件中,并结合工程实例进行数值模拟,得到爆破损伤云图及相应的爆破影响范围。然后将计算得到的爆破影响范围与现场实测值、基于常用的TCK爆破损伤模型的数值计算结果进行了对比。最后,分析了爆破影响最大半径、最大深度与岩体初始完整性指数间的关系。研究表明,爆破影响最大半径、最大深度均随岩体初始完整性指数的减小而增大,且前者的变化更为显著。基于所提出模型的数值计算结果和现场实测值较为符合;提出的损伤模型可为考虑岩体完整程度对爆破开挖影响的理论研究和工程实践提供参考。

Model of rock blasting-induced damage considering integrity of rock mass and its application

The influences of the integrity of rock mass on blasting effects are not taken into account by the current models for rock blasting-induced damage. Based on the blasting-induced damage model proposed by R. Yang et al., an elastic-plastic constitutive model for blasting-induced damage and the corresponding criterion for determining the blasting influence zone of the surrounding rock, both of which consider the initial damage of rock, are suggested by connecting the initial damage with the initial values of integrity index and acoustic wave velocity of rock mass. This model can be used to consider the influence of the initial integrity of rock mass on the blasting damage effects by changing its initial integrity index. The constitutive model is introduced into software LS-DYNA for blasting simulation in line with practical engineering. The blasting-induced damage nephogram and the blasting influence zone are obtained. The blasting influence zones obtained respectively by the suggested model, the field tests and the conventional model-TCK are compared. In the end, for the maximum influence radius of blasting and the maximum influence depth of blasting, the relations between them with the initial integrity index of rock mass are analyzed. The results show that, for the maximum influence radius and the maximum influence depth, their values decrease with the decrement of the initial integrity index of rock mass while the change of the former is more remarkable than that of the latter. The proposed model considering the initial integrity of rock mass is rational. The results obtained by the suggested numerical model agree well with those from the field tests. The proposed model can provide references for theoretical research and engineering practice, in both of which the influences of integrity of rock mass on blasting excavation should be considered.