玉磨铁路破碎板岩隧道开挖工法优选研究

Study on Optimization of Excavation Method for Fractured Slate Tunnel of Yuxi-Mohan Railway

为进一步提高破碎板岩隧道开挖时的安全性和稳定性,文章以玉磨铁路新平隧道为研究背景,利用有限差分软件对三台阶法、三台阶带仰拱一次开挖法、CD法和CRD法进行了比选分析。研究结果表明:(1)三台阶带仰拱一次开挖法控制结构竖向位移的效果较好,CRD法控制水平位移的效果较好,三台阶带仰拱一次开挖法次之;(2)三台阶带仰拱一次开挖法的最大主应力、最小主应力均最小,较传统三台阶法分别减小49. 13%、12. 23%,对应力的控制效果较好。综上可知,三台阶带仰拱一次开挖法对隧道开挖时的安全性和稳定性的控制效果较好,建议采用三台阶带仰拱一次开挖法进行施工。研究成果可为类似破碎板岩隧道的开挖施工提供参考。

In order to further improve the safety and stability of fractured slate tunnel excavation, taking Xinping Tunnel of Yuxi-Mohan Railway as the research background, three-step method, one-time excavation method with three-step inverted arch, CD method and CRD method are optimized and analyzed by using finite difference software. The results show that one-time excavation method with three-step inverted arch has the better effect in controlling the vertical displacement of the structure. CRD method has the better effect on controlling horizontal displacement, followed by one-time excavation method with three-step inverted arch. The maximum principal stress, the minimum principal stress of the one-time excavation method with three-step inverted arch are all the minimum, and they are reduced by 49.13% and 12.23% respectively compared with the traditional three-step excavation method, the stress control effect is better. In conclusion, the method of one-time excavation method with three-step inverted arch has a good control effect on the safety and stability of tunnel excavation. It is suggested that the method of one-time excavation method with three-step inverted arch be used for construction. The research results can provide reference for the development of similar fractured slate tunnel excavation construction.