基于爆破损伤的岩台保护层开挖爆破参数研究

 摘要：在现有岩石爆破损伤理论的基础上，提出考虑初始损伤的爆破损伤计算模型，推导初始损伤变量和声波波速、弹性模量以及损伤门槛值等参数间的关系式。以溪洛渡水电站主厂房岩台保护层开挖为研究背景，结合岩石爆破损伤理论，分析保护层开挖的爆破损伤效应及其主要影响因素，并导出爆破参数计算公式。对主厂房内分布较广且初始损伤程度不同的2类岩体，分别给出相应的开挖爆破参数。通过现场爆破试验、爆破振动速度测试以及钻孔声波测试，验证爆破参数的合理性以及完善爆破参数设计。研究结果表明：爆破参数设计需要考虑岩体初始损伤的影响。考虑损伤效应后，岩台保护层开挖的炮孔密集系数小于普通光面爆破参数设计值；岩体初始损伤程度较大时，应增加光爆孔的装药不耦合系数和减小炮孔密集系数；岩台开挖爆破影响深度和爆破地震效应均满足安全控制要求，爆破参数设计合理。研究成果可为同类工程提供借鉴。

Study on blasting parameters of protective layer excavation of rock bench based on blasting-induced damage

A blasting-induced damage model on account of initial damage was suggested based on the current theory of blasting induced damage on rock. The relationships among the initial damage，acoustic wave velocity，elastic modulus and threshold value of blasting induced damage were also presented. The effects of blasting induced damage and the main influencing factors under the blasting excavation of protective layer of rock bench for anchoring crane girder of the main underground powerhouse of a lager hydropower station at Xiluodu were analysed and the formulas of blasting parameters were suggested. The blasting parameters were provided owing to two engineering classifications of rock mass with different initial damages mainly located in the main underground powerhouse. The blasting tests simulating the excavation of protective layer of rock bench，the blasting vibration velocity tests and the borehole acoustic wave tests were carried out in the field，and then，the rationality of blasting parameters was proved and some supplements were added to improve the design of blasting parameters. The results showed that the initial damage of rock mass should be taken into account for the calculation of blasting parameters. The blast-hole concentration coefficient from the study was smaller than that from common smooth blasting design for the blasting excavation of protective layer of rock bench. When the initial damage of rock mass increased，the coefficient of non-coupling charge should be increased and the concentration coefficient of blast-holes for smooth blasting should be reduced. For the excavation of protective layer of rock bench，the control of both the blasting-influenced depth and the blasting seismic effects meets the requirements suggested by the hydropower station，thus，the design of blasting parameters is of rationality. The research results can provide references for similar projects.