台阶法(带仰拱)一次开挖施工技术在软岩隧道中的应用

摘要

软岩隧道采用传统台阶法开挖时易出现初期支护封闭不及时、步距超标等问题,为解决上述问题,依托蒙华重载铁路部分隧道,提出台阶法(带仰拱)一次开挖施工技术,阐述三台阶(带仰拱)和二台阶(带仰拱)施工工艺流程,从结构力学与变形响应、施工便捷性与设备空间布置等方面综合分析,提出台阶高度和台阶长度的合理设置原则,结合段家坪隧道与中条山隧道现场施工情况,分析台阶法(带仰拱)一次开挖工法的工序组织、技术要点与应用效果,总结台阶法(带仰拱)一次开挖工法的施工技术特点,并提出该工法的推广应用前景.%The untimely primary support closure and overlarge of advancing distance are often encountered during soft rock tunnel excavation by bench method. As a result, one-time bench excavation method(with inverted arch)is proposed for some tunnels on Menghua heavy haul railway; the construction flowcharts of three-bench method(with inverted arch)and two-bench method(with inverted arch)are introduced; the construction parameters such as bench height and bench length are put forward by comprehensively analyzing the structural mechanism,deformation response, construction convenience and arrangement of equipments; the construction organization, technical key points and applicable effect of the one-time excavation method of bench and inverted arch in Duanjiaping Tunnel and Zhongtiaoshan Tunnel are presented. Finally,the construction characteristics of the above-mentioned technology are summarized, and the technology is prospectively popularized.