新建隧道爆破施工对既有空洞病害隧道的动力响应分析

Caused Dynamic Response of Existing Cavity Disease Tunnel by Blasting Excavation of Newly-built Tunnel

针对相邻隧道爆破施工中对既有空洞病害隧道带来的不利影响,以既有新岭隧道旁拟建新隧道的具体工程为依托,在充分调研分析既有隧道衬砌背后空洞尺寸及分布的基础上,采用数值分析方法,对不同空洞尺寸(4.45m^2、16.23m^2)、不同分布部位(拱顶、拱腰、边墙)及不同围岩级别(Ⅲ、Ⅳ、Ⅴ)下的空洞影响进行研究。研究结果表明:衬砌背后存在空洞,对断面振速V的影响较大,影响区域主要集中在1.0~1.5倍脱空范围,表现出空洞尺寸越大对振速极值和放大效应的影响越大,且对Vy的影响要大于Vx,Vy的最大值、最大放大倍数为10cm/s、2.77倍;对主拉应力分布的影响,表现出空洞区域内衬砌应力增大,空洞附近出现减小,且空洞尺寸越大影响越大,但断面S1应力极值基本维持不变;空洞分布不利部位依次为"拱顶"、"左拱腰"、"右拱腰";既有隧道所处围岩条件越差,振速和应力越大,但放大效应基本不变。

In order to analyze the adverse effects of adjacent tunnel blasting on the existing tunnel with cavity defects,taking the project of the new tunnel beside the existing Xinling Tunnel as an example,the effects of different cavity sizes (4.45 m 2,16.23 m 2),different distribution parts (vault,arch waist,side wall),and different surrounding rock grade (Ⅲ,Ⅳ,Ⅴ) are studied by numerical analysis on the basis of thorough investigation and analysis of the types and distribution of the cavities.The results show that a cavity behind the lining has a great influence on the vibration velocity of section.The influence area mainly concentrates on the void range of 1.0~1.5 multiples.The larger the size,the greater the magnification effect on the extremum vibration velocity and amplification effect,and the influence on V y are greater than V x,and the maximum value and magnification of V y are 10 cm/s and 2.77.The influence on the distribution of main tensile stress shows that the lining stress increases in the cavity area,and decreases in the vicinity cavity,and the larger the cavity size is,the greater the influence is,but the extreme value of main tensile stress is hardly changed.The disadvantageous parts of section cavity distribution are "vault","left arch waist","right arch waist" in sequence.The worse the surrounding rock condition of existing tunnel is,the higher the vibration speed and stress are,but little change in the magnifying effect.