钻爆法施工小净距隧道的损伤与振动

Damage and vibration of small spacing tunnel constructed by drilling andblasting method

为探究隧道钻爆法开挖过程中小净距隧道围岩扰动特点,以贵安隧道工程为依托,使用ABAQUS软件并利用等效爆破方法对隧道左洞实施进尺3 m的3次全断面爆破模拟。结果表明:应力波到达岩体边界发生反射容易造成围岩拉裂损伤,因此隧道洞口附近的开挖爆破应注意洞门处的支护与监测;隧道左洞的围岩损伤主要集中在拱顶和拱底附近,损伤深度最大可达3~4 m,拱肩其次,拱腰和拱脚处的损伤最轻;隧道中夹岩峰值振速随着与爆源距离的增加,测点峰值振速先是下降,靠近已形成空区的右洞时又上升,曲线整体呈“U”形,说明岩体中的空区对振速有放大效应;隧道右洞临爆侧距爆源最近的拱腰处受到的振动扰动最明显。

This research aims to explore the disturbance characteristics of the surrounding rock of the tunnel with small spacing during the excavation process of drilling and blasting method.Based on the Guian tunnel project,ABAQUS software and the equivalent blasting method were used to simulate three full-section blasting of the left hole of the tunnel with a blasting footage of 3m.Results show that the stress waves reaching the rock boundary is prone to cause tensile failure of the surrounding rock,so in the excavation and blasting near the tunnel entrance,special attention should be paid to the support and monitoring of the tunnel door.The surrounding rock damage of the left tunnel is mainly concentrated near the vault and the bottom,and the damage depth can reach up to 3~4m,followed by the arch shoulder,and the damage at the arch waist and the bottom is the lightest.With the increase of the distance from the explosion source,the peak vibration velocity of the measurement point in the rock between the twin tunnels first decreases,and when it is close to the right hole that had formed the void area,it rises again,and the curves are approximately“U”shaped,indicating that the void area in the rock mass has an amplifying effect on the vibration velocity.The vibration disturbance at the arch closest to the explosion source of the tunnel is the most obvious.