PBA法地铁车站及暗挖区间施工对天桥影响分析

北京地铁12号线大钟寺站和大蓟区间临近大钟寺天桥,车站采用PBA工法施工,区间施工采用暗挖法,车站和区间施工对天桥存在较大的影响,需要进行风险评估与控制。根据桥梁和地铁施工情况,提出了桥梁位移控制标准。针对不同施工阶段,提出相应的风险保护措施,采用三维有限差分分析方法,分析了不同施工步下桥桩竖向及水平位移变化规律;并结合控制指标,对桥梁结构安全状态进行了评估。研究结果表明,车站和区间隧道施工风险较大,在施工控制措施外,需要辅助以桥梁保护措施;通过三维数值计算,车站主体施工阶段对桥梁位移影响最为明显,是施工控制的关键步骤;部分桥桩位移超过控制标准,结构处于不安全状态,需要进行桥梁支顶保护。研究结论可为类似工程提供一定的借鉴与参考。

INFLUENCE ANALYSIS OF PBA METHOD SUBWAY STATION AND INTERVAL TUNNEL ON PEDESTRIAN OVERPASS

The Dazhongsi Station and the Daji Intersection of Beijing Metro Line 12 are adjacent to the Dazhongsi pedestrian overpass bridge. The station is constructed by PBA method and the intersection construction uses the underground excavation method, which has a great influence on the bridge. Therefore, risk assessment and control is necessary. According to the construction conditions of bridges and subways, the bridge displacement control standards are proposed. Aiming at the different construction stages, corresponding risk protection measures are proposed, and a three-dimensional finite difference model of the adjacent bridges of stations and interval tunnels is established. With three-dimensional finite difference method, The variation law of vertical and horizontal displacement of bridge piles under different construction steps is analyzed. Combined with the control indicators, the safety status of bridge structures is evaluated. The main research conclusions: the construction risk of station and section tunnel is large. In addition to the construction control measures, it is necessary to assist the bridge protection measures. Through the three-dimensional numerical calculation, the main part of the station construction stage has the most obvious impact on the bridge displacement, which is the key step of construction control;The displacement of the part of bridge pile exceeds the control standard that the structure is in an unsafe state, and the bridge roof protection is required. The research can provide some reference for similar projects.