新建铁路隧道下穿既有运营隧道的设计与施工

新建隧道小净距、大角度下穿既有运营隧道一直是隧道设计和施工的难题之一,此类施工既要保证新建隧道施工安全,又要确保既有线安全正常运营。针对山岭隧道下穿既有铁路隧道工程实例,计算新建隧道与既有隧道的最小理论净距,在分析新建隧道与既有隧道的立交关系、所处地层条件、既有隧道现状的基础上,对立交影响段附近新建隧道的施工方案及既有铁路隧道的加固方案进行研究。严格控制爆破振动对既有隧道结构和线路的影响,对既有隧道及新建隧道的监控量测进行信息反馈及预测预报,指导现场施工,确保下穿施工时既有线行车及新建隧道施工的安全。

Design and Construction for a New Railway Tunnel Crossing below an Existing Operational Railway Tunnel

How to build a new tunnel crossing below an existing tunnel in the form of small clear distance and large angle is always one of the difficult problems in tunnel design and construction,because the construction process not only should ensure the safety of the newly-built tunnel,but also should ensure a safe and normal operation of the existing tunnel. Based on an actual project of a newly-built mountain-area tunnel crossing below an existing railway tunnel,this paper theoretically calculated the minimum clear distance between the new tunnel and the existing tunnel. And then,the paper analyzed relevant issues,including the intersection point's relationship between the new tunnel and the existing tunnel,the stratum condition,and the current situation of the existing tunnel. Furthermore,this paper researched the construction scheme for the new tunnel within the range of the intersection point and influenced zone,as well as researched the scheme for the strengthening of the existing railway tunnel.Meanwhile,the impacts of blasting vibration on the existing tunnel structure and on the track were strictly controlled. Also,monitoring and measurement as well as information feedback and geological forecast were carried out for both the new one and the existing one,so as to guide field construction,and ensure the existing one's operation safety and the new one's construction safety during tunneling the new one below the existing one.