沉管基槽开挖对周边桥梁位移影响及保护分析  

Analysis of Influence and Protection of Excavation of Immersed Tube's Foundation Trench on the Displacement of Surrounding Bridges

作　　者：周世轩[1] Zhou Shixuan(Design Institute of Civil Engineering&Architecture Dalian University of Technology,Co.,Ltd.,Dalian 116024,China)

机构地区：[1]大连理工大学土木建筑设计研究院有限公司,辽宁大连116024

出　　处：《市政技术》2023年第5期121-127,共7页Journal of Municipal Technology

摘　　要：沉管邻近既有桥梁施工时,沉管基槽开挖引起的应力释放可能会使周边既有桥梁的上、下部结构产生附加位移和附加内力,进而影响桥梁的受力和使用安全。因此,以深圳市前海湾隧道设计方案为背景,研究了沉管基槽开挖对既有桥梁的影响和不同保护措施的效果。正交试验结果表明,基槽开挖对既有桥梁桩顶位移影响的诸多因素中,淤泥层厚度影响最显著,其次为桩基与基槽坡顶净距,最后为桩基刚度。当基槽开挖引起的桩顶位移较大时,对既有桥梁周围土体加固、桥梁施加钢板桩隔离或改变开挖方式均可以减小桩顶位移。其中,土体加固对桩基的保护效果受加固范围影响较大,同时基槽开挖引起的桩顶位移基本与加固土的泊松比成正比,与加固土的弹性模量成反比;钢板桩自身施工对桩基影响较小,钢板桩嵌固地层条件对桩顶位移有很大影响,其次为钢板桩嵌固深度,钢板桩型号以及内支撑的层数对桩顶位移影响不大;改变开挖方式可实施性和可靠性较高,清淤深度以及横向清淤范围与桩顶水平位移近似呈指数关系,但纵向清淤高差的控制值会受到淤泥层厚度的影响。During the construction of the immersed tube adjacent to the existing bridges,the stress release caused by the excavation will cause additional displacement and internal force on the upper and lower structures of the surrounding bridges,and then affect the stress bearing and safety of existing bridges.Based on the design of Qianhai Bay Tunnel in Shenzhen,this paper studies the influence of the excavation of immersed tube's foundation trench on the bridge and the effect of different protection measures.The research shows that the thickness of the silt layer has the most significant influence on the pile among most of the factors,followed by the distance between the pile and trench slope,and finally the stiffness of the pile.When the pile displacement caused by foundation trench excavation exceeds the standard,the pile displacement can be reduced by reinforcing the soil,applying steel sheet pile isolation to the bridge or changing the excavation method.The protection effect of soil reinforcement is greatly affected by the reinforcement range,and the displacement of pile top is basically proportional to the Poisson's ratio of the reinforcement soil,and inversely proportional to the elastic modulus of the soil;The construction of steel sheet pile has little influence on the pile.The embedded condition of steel sheet pile has great influence on the displacement of control pile top,followed by the embedded depth of steel sheet pile.The model of steel sheet pile and the number of layers of internal support have little influence on the displacement;It is high feasible and reliable to change excavation method.The dredging depth and scope are approximately exponential with the horizontal displacement at the pile top.The control value of the dredging height will be affected by the thickness of the silt layer.

关 键 词：沉管基槽 桥梁影响 保护措施 土体加固 钢板桩 开挖方式 

分 类 号：TU753.64[建筑科学—建筑技术科学]