临近地铁既有线隧道软弱地层加固方案及桩基施工方法研究

Study on the Reinforcement Scheme and Pile Foundation Construction Method of Weak Stratum of the Existing Subway Tunnel

项目为建筑面积7.9万平的地下三层房建基坑,既有运营的地铁线从基坑西北角斜穿到东南角,施工期间确保地铁线运营安全整个项目的成败关键所在。基坑西北角地质条件差,地铁隧道上部为位于粘土层,底部为砂质粘性土,极易受到施工干扰,所以项目施工风险极大。项目采用静压钢板桩及低压注浆对隧道周进行加固,选用全套管全回转钻钻机成桩,确保了地铁既有线的安全。

The project is to build a foundation pit for an underground three-storey building with a construction area of 79,000 square meters. The existing subway line runs diagonally from the northwest corner of the foundation pit to the southeast corner. The key to the success of the entire project is to ensure the safety of the subway line during construction. The geological conditions of the northwest corner of the foundation pit are poor. The upper part of the subway tunnel is located in the clay layer and the bottom is sandy cohesive soil, which is extremely susceptible to construction interference, so the project construction risk is extremely high. The project uses static pressure steel sheet piles and low-pressure grouting to reinforce the periphery of the tunnel, and uses full-sleeve full-rotation drilling rigs to form piles to ensure the safety of the existing subway line.