近间距隧道爆破地震效应的试验研究

Experimental study on seismic effect of blasting vibration from excavation of tunnels with small interval

为了解决层状岩体中采用钻爆法修建近距离双线隧道的爆破影响问题,基于现场试验,总结了爆破衰减规律。试验结果表明,新建隧道爆破时,振动速度随着与爆源距离的增大成非线性减小；振动速度具有很强的方向效应,迎爆面径向振动速度均大于切向振动,径向振动速度对既有隧道和新建隧道围岩的损伤起主导作用：采用上下台阶开挖时,上台阶爆破冲击波对既有隧道的影响比下台阶显著。根据萨道夫斯基回归公式给出了距爆源不同距离的单段最大装药量。将爆破对新建隧道本身围岩的损伤破坏和对相邻隧道的影响结合起来综合考虑,对层状岩体中隧道爆破参数进行了优化。

In order to dispose of the influence of blasting vibration from the excavation of new tunnel on the adjacent in tunnel in stratified rockmass,site experiments were carried out and attenuation law of blasting seismic waves spreading in rockmass is attained.It is found that the vibration velocities decrease nonlinearly along with the increase of distance away from the explosion source.The vibration velocities have distinct directional effect, and the radial velocities are much greater than those in tangential direction without exception on the side wall facing to blasting source for the existing tunnel.Radial vibration velocities have the leading effects on the damage of surrounding rockmass of new and existed tunnels.When the positive benching tunneling method is used for excavation of new tunnel,the impact of shock wave generated from the upper benching blasting on the existed tunnel with respect to lower benching explosion is stronger.The permitted maximum charge quantity per one detonating period is determined for the different distance between two tunnels by the Sodev's regression formula. Finally,the explosion parameters have been optimized by the comprehensive consideration of vibration damage induced by explosion and its influence on existing tunnel.