The construction of a new tunnel is easy to cause the adjacent existing tunnel’s lining cracking and peeling which would endanger road safety .In order to decrease the influence of new tunnel construction with the drilling and blasting method on the adjacent existing tunnel ,taking the CRD method as an example ,the internal force analysis for the multiple arch tunnel under blasting load was carried out by using the finite element software ANSYS ,so as to determine the reasonable excavation footage of the tunnel .The results indicate that under the V-class surrounding condition ,the ex-cavation footage should be controlled less than 0 .8 m ,which could reduce the influence on the multiple arch tunnel ,pro-viding reference basis for the design and construction of tunnel structures .%新建隧道的施工容易造成邻近既有隧道衬砌开裂、剥落等容易危及行车安全的现象。为了减小钻爆法施工的新建隧道对邻近既有隧道的影响，以交叉中隔壁法（CRD 法）为例，利用 ANSYS 有限元软件对爆破荷载作用下的既有连拱隧道的内力进行分析，从而确定合理的隧道开挖进尺。结果表明：在V 级围岩条件下，将隧道开挖进尺控制在不超过0．8 m 为宜，可以减小施工过程中对既有连拱隧道的影响，为隧道结构的设计和施工提供参考依据。
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