隧道施工爆破诱发的围岩累积损伤规律研究

Study on cumulative damage law of surrounding rock induced by blasting during tunnel construction

隧道钻爆法推进式爆破过程会不可避免地对岩体造成损伤,岩体累积损伤源于持续的岩体动力响应。然而,目前尚缺乏量化隧道各分段炸药陆续爆破、隧道推进式重复爆破对围岩造成累积损伤值的计算方法。文章以某隧道工程为研究背景,提出一种模拟隧道各分段炸药陆续爆破、推进式重复爆破的方法,并量化了各个工况对围岩造成的累积损伤程度,最终结合现场测试数据佐证了该方法的可靠性。结果表明:(1)计算大规模起爆引起的损伤时,采用等效荷载方式模拟爆破具有优势;(2)隧道单循环进尺开挖诱发的围岩损伤是多段炸药延期爆破叠加引起的,主要受邻近辅助眼爆破的影响;(3)多循环进尺的爆破开挖会诱发围岩损伤的累积,且累积过程主要受当前爆破进尺和上一个爆破进尺影响;相比于单循环进尺,多循环进尺对隧道中间侧墙的损伤累积程度增大26.7%。

During the propulsive blasting process of tunnel drilling and blasting method,it is inevitable to cause damage to the rock mass.The cumulative damage of rock mass originates from the continuous dynamic response of rock mass.At present,there is still no quantification method to calculate the cumulative damage of surrounding rock subjected to the successive blasting of tunnel each subsection and the repeated blasting of tunnel propulsion.Relying on a tunnel project,a method is proposed to simulate the successive blasting and propulsive repeated blasting of each tunnel subsection,and the cumulative damage extent caused by each working condition to surrounding rock is quantified.The feasibility of this method is proved by field test data.The results show that:(1)when calculating the damage simulation of large-scale blasting,it is advantageous to use equivalent load to simulate blasting load;(2)the surrounding rock damage induced by single-cycle footage excavation of the tunnel is caused by the superposition of multiple stages of delayed blasting,which is mainly affected by the adjacent auxiliary;(3)the blasting excavation of multi-cycle footage will also induce the accumulation of surrounding rock damage,and the accumulation process is mainly affected by the current blasting footage and the previous blasting footage;compared to the single-cycle footage,the cumulative damage extent of the tunnel middle side wall caused by the multi-cycle footage increased by 26.7%.