新建隧道施工对临近既有隧道结构安全性影响分析

新建隧道与既有隧道间距较近时,新建隧道的开挖导致围岩应力发生重分布,对既有隧道的结构产生影响,为此针对包西铁路通道新宝塔山隧道出口端,用有限元方法进行了数值模拟分析,并进行施工监控量测,对计算结果和监控量测结果进行分析,结果表明:新建隧道开挖将引起围岩应力重分布,使既有隧道衬砌结构的安全系数有所降低,其降低程度与两隧道间距有关,间距越小其影响程度越大。新建隧道的开挖对既有隧道临近开挖一侧的衬砌结构影响最大。

Numerical Simulation Analysis of the Influence of a New Tunnel Construction on the Safety of Existing Adjacent Tunnels

When a new tunnel is adjacent to existing tunnels, the excavation of the new tunnel shall cause the re-distribution of surrounding rock stress, and influence structure of the existing tunnel. Therefore, a numerical simulation analysis and construction surveying and measurement are carried out with the Finite Element Method for the exit of New Baota Mount Tunnel in Baotou-Xi＇ an Railway. Analysis based on the results of computing, surveying and measurement shows： The excavation of a new tunnel shall cause the re-distribution of surrounding rock stress, and the safety coefficient of lining structure of an existing tunnel shall decrease. Its reduction is related to the distance between two tunnels ： the smaller the distance is, the more influence there is. Moreover, the lining structure close to the excavation side shall be influenced to a greater extent.