暗挖地铁车站端头桩结构优化方案

Optimal Scheme of End Pile Structure of Underground Subway Station

北京地铁昌平线小营西路车站为暗挖车站,采用PBA工法施工,车站两端的区间隧道采用盾构法施工。因此针对设计的玻璃纤维筋端头桩,分析了盾构掘进和磨桩施工给工程带来的不利影响,并在该基础上,对端头桩的桩体结构和施工方法进行了优化,即将每根端头桩体结构分为2段、分2个阶段施工。首先施工端头桩的“下部钢筋混凝土桩+中部素桩+上部M5砂浆桩”,待盾构通过端头桩部位后,采用人工挖孔的方法施工端头桩上部的钢筋混凝土桩体。实践证明,该端头桩结构形式和相应的施工方法不但确保了盾构通过后的桩体安全性,也大幅度降低了盾构掘进通过端头桩的时间。

Xiaoyingxilu station of Beijing Subway Changping Line is a underground excavation station, which is constructed by PBA construction method, and the running tunnels at both ends of the station are constructed by shield tunneling method. In view of the designed glass fiber reinforced end pile, the adverse impacts of shield tunneling and pile grinding on the project are analyzed. The pile structure and construction method of the end piles are optimized, namely the end pile structure is divided into two sections and constructed by two stages. Firstly, “the lower reinforced concrete pile + the plain pile in the middle part + the M5 mortar pile in the upper part” is constructed. After the shield passed through the piles,the upper reinforced concrete piles are constructed by manual digging. This construction method not only ensures the safety of the piles after the shield tunneling through the piles,but also greatly reduces the time of the shield tunneling through the end piles.