重载铁路隧道仰拱施工关键技术应用——以中条山隧道为例

为解决软岩隧道仰拱采用传统台阶法施工易出现的初期支护封闭不及时变形大,仰拱二衬采用传统栈桥施工存在的质量缺陷多、安全性差的问题,依托浩吉铁路中条山隧道对仰拱施工技术进行了研究和创新,提出仰拱和下台阶一次开挖技术和仰拱二衬大区段技术。同时针对高地应力、第三系泥岩地层及富水地段等不良地质仰拱施工技术进行了研究和优化。研究结果表明:仰拱和下台阶一次开挖快速封闭成环技术在变形控制、安全性、工效均比传统台阶法好;仰拱二衬采用24m大区段技术在仰拱整体质量,安全性均比传统栈桥施工要好;高地应力段采取早封闭、强支护等措施有效解决了变形较大的问题。第三系泥岩地层采用碎石换填并注浆加固解决了仰拱承载力不足和基底通水问题。富水地段增设独立排水系统解决了地下水对仰拱的侵蚀,降低了地下水对仰拱的作用力。通过浩吉铁路全线多条隧道的应用以及一年多的铁路运营检验证明了仰拱系列施工技术的安全性和适用性,对软岩隧道仰拱施工具有较高的应用价值。

Application of key technologies in invert construction of heavy haul railway tunnel- taking Zhongtiaoshan tunnel as an example

The inverted arch of soft rock tunnel is constructed by traditional bench method, which is prone to problems that the initial support is not closed timely and the deformation is large. The traditional trestle used for the two lining of inverted arch also exists quality defects and poor safety. Moreover, the inverted arch is also influenced by groundwater, high ground stress and adverse geology. In order to solve the above problems, based on Zhongtiaoshan tunnel of Haoji railway project, the invert construction technology was explored and innovated. In addition, the technology of one-time excavation of inverted arch and lower bench and large section technology of inverted arch two lining were proposed. The main conclusions are as follows: Compared with traditional bench method, one-time excavation of inverted arch and lower bench are better in terms of the deformation control, safety and efficiency;The overall quality and safety of inverted arch two lining are higher than those of traditional trestle construction;The problem of large deformation is effectively solved by adopting measures such as early closure and strong support in high geostress section. In the Tertiary strata, gravel replacement and grouting reinforcement are applied to solve the insufficient bearing capacity of inverted arch and water supply of foundation. Furthermore, the independent drainage system is added in the water-rich section to reduce the erosion of groundwater and the force of groundwater on the invert. In summary, through the application of several tunnels along the entire line of Haoji railway and one-year railway operation inspection, the safety and extensive applicability of invert series construction technology are proved, which has high application value for invert construction of soft rock tunnel.