降雨对隧道浅埋段施工力学效应影响研究

Research on construction mechanical effect of shallow buried tunnel under rainfall condition

降雨入渗对隧道浅埋段洞室稳定性有着重要影响。文章依托京沪高速济南连接段老虎山隧道,首先采用数值模拟方法分析了降雨条件下隧道洞口浅埋段渗流场演化规律;在此基础上,通过流固耦合数值模型对不同降雨入渗时间下双侧壁导坑法施工过程中围岩应力、支护结构受力变形特征进行研究,得出以下结论:降雨对洞口40m范围隧道影响较大,入渗形成的地下水位线贯穿隧道洞身,其中土石交界处孔隙水压力值较大;降雨入渗使得围岩应力、支护结构变形增大,支护结构压应力增大、但拉应力减小;其中降雨结束时影响最大,降雨结束20d左右影响基本消除。

Rainfall infiltration would significantly influence the stability of shallow buried tunnel in construction period.Laohushan tunnel,as a connection line of expressway between Peking and Shanghai,is located in Jinan city.Based on the tunnel,the evolution law of seepage field in the shallow buried section of tunnel entrance were firstly studied by numerical simulation under rainfall conditions.Furtherly,construction mechanical response of double-side-drift excavation method were analysed by means of fluid-solid coupling model.And stress of surrounding rock,stress and deformation of primary support were mainly studied under different infiltration times.It could be conclued that stability of tunnel 40 m long near entrance were seriously imflunced by rainfall.Underground phreatic line caused by rainfall infiltration run through the whole tunnel.And pore water pressure lying in the interface between soil and rock were relatively large.Due to rainfall infiltration,stress of surrounding rock and deformation of primary support increased.And compressive stress of primary support increased,but the tensile stress decreased.When the rain was over,the influence became the largest,and the rainfall influence was eliminated about 20 days after the end of rainfall.