浅埋山岭隧道软岩段塌方原因分析及处理技术

摘要

文章以某浅埋山岭隧道软岩段塌方处理为工程背景,总结和分析了软岩段隧道塌方的原因,认为:(1)山岭隧道软岩段允许爆破振动速度10 cm/s的指标偏大,在分步开挖时,反复的爆破振动会超过岩体的爆破振动耐受值;(2)在软岩偏压段,监控量测频率应当随隧道开挖工法的变化而变化,需建立动态的隧道塌方预警系统;(3)对塌方段以"稳定塌体,填充塌腔,超前注浆,谨慎通过"的总体处理原则,加强对山岭隧道软岩段爆破振动速度的控制,采用"横分纵错,一次起爆,分步延时"爆破技术降低爆破振动,可快速安全地通过软岩隧道段.%Based on a shallow-buried mountain tunnel in soft rock,the causes of a tunnel collapse in soft rock are analyzed and summarized.It is concluded that:1)the index of allowed blasting vibration velocity of 10 cm/s is too large for soft rock mountain tunnels, and repeated blasting vibrations will exceed the tolerance value of the rock blasting vibration during excavation by steps; and 2) the frequency of monitoring and measuring should vary with changes to the tunnel construction method,which is necessary to establish a dynamic warning system for tunnel col-lapses.The blasting vibration velocity of a mountain tunnel in soft rock can be controlled more effectively using the general principles of stabilizing the collapse cavity,filling the collapse cavity,advance grouting of the collapse cavi-ty and cautious passage.The blasting vibration velocity can be reduced by using different arrangements of drill holes at various sections,simultaneous initiation and millisecond delay initiation,which will facilitate rapid passage in the soft rock section.