Ⅴ级围岩浅埋大跨双洞隧道施工力学行为及安全净距研究

Construction Mechanics Behavior and Safety Clearance of Shallow Long-span Double-hole Tunnel UnderⅤGrade Surrounding Rock

为研究交叉中隔墙法(CRD)在浅埋大跨双洞隧道Ⅴ级围岩条件下的适应性,基于ANSYS有限元软件进行了二次开发,依托将军山隧道建立计算模型,开展了洞室开挖各施工工序下“围岩-支护”系统的动态施工力学行为研究,并对洞口段安全净距做了进一步的探讨。结果表明:隧道各开挖工序下围岩变形均呈突增态势,前四步开挖位移变化较大;洞室围岩应力随着开挖工序的进行在不断调整,最大主压应力总体上呈较高水平;隧道塌落区面积随着开挖工序的不断进行而增大;钢拱架的弯矩随着开挖工序的不断进行而调整;初期支护和二次衬砌在整个施工过程中的安全系数均满足要求。研究成果可为类似隧道工程的设计和施工提供参考。

In order to analyze the adaptability of cross partition method(CRD)of shallow and large-span double-hole tunnel under the condition ofⅤsurrounding rock,the secondary development is carried out based on ANSYS finite element software,the calculation model is established based on the Jiangjunshan tunnel.The dynamic construction mechanical behavior of“surrounding rock-support”system under each construction procedure of cavern excavation is analyzed,then the safety distance of the opening section is further discussed.The results are as follows.The deformation of surrounding rock shows a sudden increase under each excavation procedure of tunnel,the displacement of the first four steps varies greatly.The stress of surrounding rock is constantly adjusted with the excavation process,the maximum principal compressive stress is relatively high in general.The area of tunnel collapse increases with the continuous excavation process.The bending moment of the steel arch is adjusted with the continuous excavation process.The minimum safety factor of primary support and secondary lining in the whole construction process which all can meet the requirement.The research results can provide reference for the design and construction of similar tunnel projects.