多孔微差爆破下岩石损伤演化规律研究

Study on Damage Evolution Law of Rock Under Multi Hole Millisecond Blasting

目前山岭隧道开挖中大多数采用钻爆法,但爆破施工时难免会出现超欠挖、围岩损伤破坏严重等现象,直接影响施工安全。通过建立本构模型和有限元分析软件ANSYS/LS-DYNA,对不同节理裂隙角度下的爆生裂纹规律以及逐孔起爆、间隔起爆两种起爆顺序和不同微差间隔时间下岩石损伤演化规律进行研究,得出当节理裂隙与炮孔中心连线成60°~90°夹角时岩体破碎效果较差,当节理裂隙与炮孔中心连线成45°时岩体破碎效果最好;间隔起爆下中间孔先起爆的爆生裂纹扩展长度分布较为均匀,可将其应用于辅助眼处,以便于岩石破碎以及减少大块率,为实际隧道工程提供了技术参考。

At present,the drlling and blasting method is mostly used in the excavation of mountain tunnel,but the phenomenon of over excavation and under excavation and serious damage of surrounding rock will inevitably occur during the blasting construction,which will directly affect the construction safety.Through the establishment of constitutive model and finite element analysis software ANSYS/LS-DYNA,the blasting crack law under different joint fissure angles and the evolution law of rock damage under hole-by-hole initiation and interval blasting sequences as well as different millisecond interval times are studied.It is concluded that the rock fragmentation effect is poor when the joint fissure and the center line of blast hole are at an angle of 60°~90°,and the rock fragmentation effect is best when the joint fissure and the center line of blast hole are at an angle of 45°;under the condition of interval initiation,the propagation length of the blasting crack initiated first in the middle hole is relatively uniform,which can be applied to the auxiliary hole to facilitate rock fragmentation and reduce the rate of large blocks.It provides a technical reference for the actual tunnel engineering.