洞桩法侧向挖掘轻轨车站引起的大跨斜拉桥桩基位移的控制

DEFORMATION CONTROL OF PILE FOUNDATIONS FOR A LONG-SPAN CABLE-STAYED BRIDGE UNDER CONSTRUCTION OF A LIGHT RAIL STATION WITH THE PILE-BEAM-ARCH METHOD

为保证大跨斜拉桥桩基在洞桩法(PBA法)侧向暗挖轻轨车站过程中的稳定,采用复合锚桩对挖掘空间与桥梁基础间的土体进行注浆加固。通过有限元软件分别对注浆加固前、后桥梁桩基础的位移和桥梁结构内力进行分析。结果表明:在轻轨车站空间的挖掘过程中,基桩最大位移发生在车站主体上部土体开挖结束阶段;注浆加固支护减小了开挖面周边土层松动区范围和塑性区范围,桩基础沉降较未加固支护情况减小了28.7%;在考虑支座位移的情况下,桥梁能满足承载能力极限状态和正常使用极限状态的设计要求。

The soil between tunnelled spaces and bridge abutments was supported and reinforced by grouted with composite bolt piles to ensure security and stability of a long-span cable-stayed bridge before tunnelling a underground light rail station along sides of pile founndations of the bridge with pile-beam-arch(PBA)method.The settlement of piles and the structural internal forces of the bridge before and after grouted reinforcement were studied by FEA.The results showed that the maximum settlement of piles occurred at the end of tunnelling the upper soil strata of the station.After grouted reinforcement,the loose range and plastic range around the tunnelled surface were reduced.The settlement of piles was reduced by 28.7% compared with that of the unreinforced state.The calculation results showed that the bridge structure could meet the specification requirements in the ultimate bearing capacity and normal service state considering displacement of bearings.