暗挖地铁车站空间交叉结构施工对邻近扩大基础桥梁影响分析

Analysis on the Influence of Metro Station’s Spatial Cross Structure Construction on the Adjacent Bridge with Expanded Foundation

北京地铁12号线安贞桥站采用暗挖分离结构形式侧穿安贞东桥,桥梁下部结构形式为斜腿刚构,下接扩大基础。在安贞东桥南北两侧,车站的施工横通道和车站主体结构的相交部位形成空间交叉结构,其施工将对桥梁安全造成威胁。为减小交叉部位施工对桥梁的影响,提出"超前深孔注浆"和"超前深孔注浆和地表隔离桩联合使用"两种保护措施,并采用数值模拟方法对两种保护方案的实施效果进行计算分析。结果表明:仅采取超前深孔注浆加固措施,桥梁扩大基础沉降超出指标要求,采用"超前深孔注浆和地表隔离桩联合使用"的保护措施可有效控制基础沉降,因此确定后者为对安贞东桥的保护措施。最后分析了目前施工阶段桥梁下部结构和扩大基础沉降监测数据较大的原因,探讨了后续的施工对策。

The Anzhenqiao Subway Station of Beijing Metro Line 12 is near Anzhen West Bridge and Anzhen East Bridge. Restricted by the location of the bridge foundation, the Anzhenqiao Subway Station structure is designed as two separated tunnels. The substructure of the adjacent Anzhen East Bridge is composed of slant-legged rigid frame and expanded foundation. On the north and south sides of Anzhen East Bridge, the construction cross passage of the station and the main structure form spatial cross structure, and the construction of this site will have an adverse impact on the safety of the bridge. In order to reduce the impact of the cross section construction on the bridge, two kinds of protective procedures of"advanced deep hole grouting" and "advanced deep hole grouting combined with surface isolation piles" are put forward. Numerical simulation method is used to calculate and analyze the effects of two protection schemes. The results show that the settlement of the expanded foundation will exceed the control index if the advanced deep hole grouting reinforcement procedure is taken, and the settlement of the expanded foundation can be effectively controlled by taking the procedure of "advanced deep hole grouting combined with surface isolation pile". Therefore, the latter protection procedure is employed for the Anzhen East Bridge. At last, the reason why the bridge substructure and foundation monitoring data is larger at the present construction stage is analyzed, and the subsequent construction measures are discussed.