地铁隧道下穿桥梁桩基托换力学行为与参数研究

Research of Pile Foundation Mechanics Behavior and Parameters Underpinning of Subway Running Tunnel Passing Under the Existing Bridge

以深圳地铁7号线黄木岗站区间隧道穿越华强立交桥桩基为工程背景,分析了隧道穿越桥梁下方桩基时的主动托换和被动托换的荷载转换、桩基沉降规律及主动托换时不同设计参数对桩基沉降的影响规律。结果表明:托换梁的挠曲变形是桩基沉降的主要因素,主动托换时千斤顶的顶升作用可有效抵消托换梁的挠曲变形,其托换效果优于被动托换;主动托换时,顶升位移为1.68mm时为最佳截桩位置,此时截桩能有效减小托换工艺对桥梁上部结构影响;在一定范围内,托换结构的桩长越长、桩径越大、梁高越高,被托换桩顶处竖向位移差越小,梁宽对位移差的影响程度不明显。

Traversing Huaqiang flyover pile foundation by No. 7 line of subway in Shenzhen during the tunnel construction of Huangmugang station is taken as construction background, the load transfer of active underpinning and passive underpinning when tunnel traverses the pile foundation of flyover, settlement rule of pile foundation and influencing rules on settlement of pile foundation by different parameters when active underpinning are introduced. It turns out that the flexural deformation of underpinning beam is the main factor of pile foundation settlement. Jack-up effect of jack can offset the flexural deformation effect of underpinning beam when active underpinning and its underpinning effect are better than passive underpinning effect. When active underpinning, the best cut pile position is 1.68mm of top displacement, and at this time, cut pile can effectively reduce the influences on upper structure of bridge by underpinning technology. Within certain range, the pile length of underpinning structure is longer, the pile diameter is larger and beam depth is higher. When vertical displacement of passive underpinning has small differential value, the influences on displacement differential value by beam are not obvious.