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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。
The existing constitutive model of blasting damage can not consider the effect of completeness of rock mass on blasting effect. Therefore, the blasting damage model proposed by Yang et al was improved, and the constitutive model of elastoplastic blasting damage considering the initial damage was established and the damage criterion for evaluating the surrounding rock affected by blasting was proposed. The constitutive model includes the relationship between initial damage variables, rock mass integrity index and acoustic wave velocity, and considers the influence of integrity on blasting damage by using the change of initial integrity index of rock mass. The model was introduced into LS-DYNA numerical software, and numerical simulation was carried out with engineering examples to obtain the blast damage cloud image and the corresponding blasting influence range. Then the calculated range of impact of blasting is compared with the measured values of the field based on the numerical results of the commonly used model of blasting damage of TCK. Finally, the relationship between maximum radius of blasting influence, maximum depth and initial integrity index of rock mass is analyzed. The results show that the maximum radius and maximum depth of blasting increase with the decrease of initial integrity index of rock mass, and the former has more significant changes. The numerical results based on the proposed model are in good agreement with the field measurements. The proposed damage model can provide reference for the theoretical research and engineering practice considering the integrity of rock mass in blasting excavation.