岩石地基中群桩基础对相邻车站隧道影响分析——以重庆地铁1号线七星岗站为例

桩基加载会造成周围土体的位移和应力变化,继而对邻近隧道的内力和位移造成影响,特别是在群桩基础的作用下,这种影响不可忽视。以岩质地基中大跨径车站隧道与群桩基础的相互影响为研究对象,采用有限元软件对群桩位于隧道顶板上方、隧道侧壁破裂面以下及隧道底板3种模型进行对比分析,重点比较桩基加载工况下隧道位移变化及衬砌内力变化。分析表明当桩基础荷载大,隧道洞跨大时,置于隧道顶板的桩基础会明显降低衬砌安全系数,使衬砌结构遭受破坏;通过数值模拟对比分析得出当桩基位于隧道侧墙破裂面以下,且临近隧道侧墙的桩基加长至隧道拱底标高时,能大大降低对隧道衬砌结构和位移的影响,并能确保运营隧道的结构安全。

Analysis on Influence of Pile Group Foundation in Rock Base on Adjacent Station Tunnels:Case Study on Station on No.1 Line Qixinggang of Chongqing Metro

The loading of pile foundations may cause displacement and stress variation of the surrounding ground, which may further pose impact on the internal force and displacement of adjacent tunnels, especially under the action of pile group foundations. In this paper, comparison and contrast is made among 3 models, including the model with the pile group being above the tunnel roof, the model with the pile group extending below the failure surface of the tunnel sidewall and the model with the pile group extending below the tunnel floor, by means of finite element software, and the variation of the displacement of the tunnel and the variation of the internal force of the lining under the loading of the pile foundation are analyzed, with a large span rock station of Chongqing Metro as an example. The analysis shows that: Under the condition of huge pile foundation loading and big tunnel span, the lining structure of the tunnel will be damaged when the pile foundation is located above the tunnel roof; The influence of the pile group on the tunnel lining and the displacement can be minimized when the pile foundation is extended below the failure surface of the sidewall and the pile foundation adjacent to the side wall is extended below the tunnel floor. 