钻爆施工隧道围岩爆破损伤累积效应研究

为了合理选择施工方案并为设置安全防护措施提供依据,降低施工诱发地质灾害的风险,研究了隧道施工过程中掌子面多次爆破振动对隧洞围岩带来的累积损伤影响。首先,以质点振动峰值速度作为围岩损伤判定标准,根据围岩损伤程度利用强度折减法设置围岩力学参数,对理论公式进行推导。其次,通过软件进行多次爆破开挖的数值模拟,分析得到爆破损伤的分布规律和范围。最后,量化分析并拟合成果数据,对比不同围岩等级、不同部位爆破损伤的累积效应。结果表明:爆破损伤的累积效应非常明显,且与文献中的测试数据接近;掌子面前方的累积效应最大,其他部位较为接近;Ⅳ级围岩的爆破损伤分布范围最大,其次为Ⅲ级围岩,最小为Ⅴ级围岩;隧道施工过程中考虑岩体安全厚度、安全防护措施等内容时,应当计入累积损伤效应增大系数。研究成果可以广泛应用于水利、交通、矿山等工程项目中,为隧道掘进施工方案和防护措施制定提供数据参考,为安全施工提供保障。

Study on cumulative blasting damage effect on surrounding rock of tunnel excavatedwith drilling-blasting method

In order to provide the bases for reasonably selecting construction scheme and setting up safety prevention measures and then lowering the construction-induced geological risk，the cumulative damage effect from the blasting vibrations of the excavation face for many times on the tunnel surrounding rock during the excavation of tunnel is studied herein. Firstly，the mechanical parameters of the surrounding rock are set with the strength reduction method according to the damage degree of the surrounding rock by taking the peak particle vibration velocity as the criteria for judging the surrounding rock damage，and then the theoretical formula is derived. Secondarily，the distribution law and range of the blasting damage is analyzed and obtained through the numerical simulations made with the relevant software on the blasting excavation for many times. Finally，the achieved data are quantitatively analyzed and fitted，while the cumulative blasting damage effects on different grades and positions of surrounding rock are compared. The result shows that the cumulative effect of blasting damage is quite significant and approaches to the measured data from the literature concerned. The cumulative effect is largest in front of the excavation face and is relatively approximate on the other locations. The blasting damage distribution range of the surrounding rock of Grade IV is the largest， while the secondary is the surrounding rock of Grade III and the smallest is the surrounding rock of Grade V. When the safety thickness of rock mass，safety protection measures，etc. are considered during the construction of tunnel，the enhancing coefficient of the cumulative damage effect must be taken into account. The study result can not only be widely applied to the projects of water conservancy，transportation and mining，etc. ，but also can provide data references for tunneling scheme and the relevant protection measures as well as the guarantee for safe construction.