隧道密贴下穿既有车站差异性沉降控制研究

Research on the differential settlement control of tunnel closely passing underneath existing station

新建隧道密贴下穿既有车站容易引起既有结构产生沉降,尤其是变形缝处会产生差异性沉降,可能会影响既有车站安全使用。文章依托北京地铁苏州街站项目,通过数值模拟分析了千斤顶的顶升作用下既有车站变形缝处的沉降规律。结果表明:平顶直墙暗挖+千斤顶主动托换的施工方法可以有效地控制既有车站沉降,其沉降最大值为-2.04 mm;密贴下穿施工时既有结构变形缝处会产生一定差异性沉降,因受上方覆土的影响单层段沉降会大于双层段的;承插口位置变形缝处应力先是随着施工开挖增大,而后随着千斤顶顶力的施加变小,证明承插口和千斤顶均能缓解既有车站变形缝处差异性沉降。

Newly built tunnels closely sticking underneath the existing subway station are likely to cause the existing structure to settle,especially the differential settlement at the deformed joints,may affect the safe use of existing stations.For this,relying on the Beijing Subway Suzhou Street Station project,this paper,through numerical simulation,analyzes the deformation and settlement law of the newly built tunnel undernearth the existing subway station under the jacking effect of the jack.The research has drawn the following conclusions:that the construction method of flat-topped straight wall+jack active underpinning can effectively control the settlement of the existing station,and the maximum settlement is-2.04 mm;during the close-fitting underpass construction,a certain differential settlement will occur at the deformation joints of the existing structure.The settlement of the single-layer section will be greater than that of the double-layer section due to the influence of the overburden;the stress at the socket first increases with the construction excavation,and then with the application of jack jacking force becomes smaller,which proves that both sockets and jacks can alleviate the differential settlement at the deformation joints of the existing stations.