大型地下厂房开挖爆破损伤影响范围及评价研究

摘要

Aiming at short-hole bench blasting excavation of the main powerhouse of Xi Loudu hydroelectric power plant,the curve of load on blasthole and the constitutive relation model of rock dynamic damage considering both compression fracture and tensile damage were obtained according to the C-J detonation theory and the statistical theory of strength.The curve of load and the constitutive relation were applied in software FLAC3D for the establishment of the three-dimensional finite difference numerical simulation model of single-hole blasting.The characteristics of rock blasting-induced damage zone were obtained through analyzing dynamic responses of rock-blasting.Meanwhile,blasting tests,tests of acoustic wave velocity in borehole and blasting vibration tests were conducted on site.The comparison of results obtained from field tests,the numerical simulation based on TCK constitutive relation model and the numerical simulation considering both compression fracture and tensile damage was also made in order to verify the rationality of the proposed model.The results showed that the rock blasting-induce zone expands with decrease in excavation depth due to the effects of ground free surface of excavtion layer;the horizontal radius of the blasting-induced zone reaches its maximum due to the effects of top damage of blasthole,and the radius increases significantly with increase in single-hole charge amount;the peak value of horizontal-radial vibration velocity corresponding to the maximum radius affecting damage can be used as the criterion of blasting-induced damage;the main blasting-induced damage extension direction is along the horizontal-radial direction instead of the vertical depth.The numerical results were reasonable and provided a reference for the similar blasting excavation projects.%针对溪洛渡主厂房浅孔台阶开挖爆破工程，根据C－J爆轰理论和强度统计理论等分别得到炮孔壁上爆炸冲击荷载曲线和考虑压、拉损伤的岩石动力损伤本构关系。在 FLAC3D数值软件中应用该爆炸荷载曲线和本构关系，并建立模拟单个垂直炮孔起爆的三维有限差分计算模型，分析岩石爆破动力响应，得到爆破损伤影响范围特性。同时在现场进行了爆破试验、钻孔声波测试和爆破振动速度测试。将现场试验、基于 TCK 体积拉伸损伤模型的数值计算与考虑压、拉损伤的数值计算的结果对比，验证压、拉损伤数值模型的合理性。研究成果表明，受地表自由面影响，岩石爆破损伤影响范围随深度增加而减小。炮孔顶部损伤影响水平半径最大，且该半径随单孔炸药量增大而显著增大；与最大损伤影响半径对应的水平径向质点峰值振动速度可作为爆破损伤安全判据；相对深度方向，水平径向为爆破损伤的主要扩展方向；数值计算结果较为合理，研究成果可为类似开挖爆破工程提供参考。