深厚淤泥层大型沉井突沉机制及预警指标研究  

Study of Mechanism and Early Warning Indexes of Abrupt Sinking of Large Open Caisson in Deep Soft Clay Layers

作　　者：马远刚 刘彦峰 黄锐 MA Yuan-gang;LIU Yan-feng;HUANG Rui(China Railway Bridge Science Research Institute,Ltd.,Wuhan 430034,China;StateKey Laboratory for Health and Safety of Bridge Structures,Wuhan 430034,China)

机构地区：[1]中铁大桥科学研究院有限公司,湖北武汉430034 [2]桥梁结构健康与安全国家重点实验室,湖北武汉430034

出　　处：《桥梁建设》2019年第A01期33-38,共6页Bridge Construction

基　　金：中国中铁股份有限公司科技研究开发计划项目(2014-重大-02)~~

摘　　要：为明确大型沉井基础穿越深厚淤泥层时发生突沉的原因及预警指标,降低施工风险,以温州瓯江北口大桥中塔沉井(长66m、宽55m、高68m)为背景进行分析。基于下沉过程中刃脚踏面反力、刃脚根部结构应力及几何姿态等现场监测数据,分析沉井启动突沉的力学机制,研究预警体系指标及其取值。结果表明:强结构性淤泥土的应变软化特性是造成沉井突沉的主要原因;突沉启动前,沉井高程小幅下降,刃脚踏面反力显著减小,刃脚根部结构应力增大并有向内挠曲变形趋势;沉井顶面高程、刃脚踏面反力、刃脚根部结构应力可以作为沉井启动突沉的预警指标。In order to confirm the causes of abrupt sinking of a large open caisson when it is lowering through the deep soft clay layers and to make early warning so as to decrease construction risk,the caisson of central pylon of Oujiang North Estuary Bridge in Wenzhou is cited as an example for analysis.The caisson measures 66 m×55 m,68 m in height.Based on the measured data,including the reaction force of the landing pitch of the cutting edge,structural reaction force at the root of the cutting edge,and the geometrical position,the mechanical property of the abrupt sinking of caisson was analyzed,the indexes of the early warning system and the values of the indexes were studied.The results show that the strain softening characteristic of the strong structural clay is the main cause of the abrupt sinking of the open caisson.When the an abrupt sinking is going to happen,the elevation of the caisson slightly decreases,the reaction force of the landing pitch of cutting edge distinctively falls,and the structural stress in the root of the cutting edge increases and shows the sign of inwardly flexural deformation.The caisson-top elevation,reaction force of the landing pitch of cutting edge and the structural stress in the root of the cutting edge can be taken as the early warning indexes.

关 键 词：悬索桥 沉井基础 淤泥土层 现场监测 突沉 预警指标 

分 类 号：U443.131[建筑科学—桥梁与隧道工程] U445.557[交通运输工程—道路与铁道工程]