高地应力软岩大变形小净距隧道支护形式及施工顺序探讨

Support Form and Construction Sequence for Soft Rock Tunnels with Small Spacing, High Stress and Deformation

山岭铁路受地形影响及车站设置需要,车站延伸到隧道的实例越来越多,燕尾式的隧道平面布置形式是其中最常见的一种,在小净距隧道施工时由于后行隧道对先行隧道的影响,造成初期支护、二次衬砌开裂及仰拱隆起等问题。文章以兰渝铁路新城子隧道两单线小净距段施工为例,分析探讨了高地应力、软岩大变形、小净距隧道支护形式及左右洞仰拱与二次衬砌的施工顺序,可为类似隧道施工与管理提供借鉴。

Increasingly, stations are being extended to tunnels due to the effects of topography on mountain rail-ways and the requirements of the stations. A forked tail tunnel arrangement is the most popular one, but the concomi-tant effect of the following tunnel on the antecedent tunnel during construction of a tunnel with small spacing causescracking of the primary support and secondary lining as well as heaving of the invert, which continues to trouble en-gineers. Different problems are encountered by different tunnels because of the complexities and variations of geo-logical environments. Using the construction of two single-line sections with small spacing for the Xinchengzi tunnelon the Lanzhou-Chongqing railway as an example, the support form for a soft rock tunnel with small spacing andhigh geostress and deformation, as well as the invert construction sequence of the left and right lines and secondarylining, are analyzed and discussed.