超大型沉井降排水下沉施工

泰州大桥北锚碇沉井基础长67.9m、宽52m、高57m,在沉井下沉的初期,采用降排水下沉。降排水下沉施工成本相比不排水下沉低,且下沉效率高,易控制,可形成良好的下沉导向,并确保沉井的下沉速度和精度,适宜在粉细砂、软塑性亚黏土等地质条件下采用。文章以泰州大桥北锚碇沉井基础为例,介绍了超大型沉井降排水施工的降排水下沉施工工艺。     

陆上特大型沉井施工技术

泰州大桥主桥采用主跨2×1080m三塔两跨两锚碇悬索桥,其中南、北锚碇基础为特大型沉井,矩形平面尺寸为67.9m×52.0m,高度分别为41m,57m。针对锚碇基础覆盖层深厚、基础尺寸巨大、沉井下沉深度深等特点,通过施工技术的攻关,顺利完成了砂桩复合地基处理、沉井制作和拼装、钢壳沉井混凝土填充、混凝土沉井接高施工、水力机械冲吸式排水下沉和空气吸泥机吸泥下沉等多项施工工序,为今后陆上特大型沉井施工提供了借鉴。文章简要介绍了南、北锚碇陆上特大型沉井的施工技术。     

泰州大桥南锚碇沉井基础深度效应研究

重力式锚碇基础在计算中通常简化为浅基础,并不考虑深度效应的影响,较为不经济。泰州大桥南锚碇沉井埋置深度达42 m,为将深度效应考虑到锚碇稳定性计算中,故采用有限元法对泰州大桥南锚碇沉井基础的深度效应进行研究。通过计算对比不同埋置深度条件下锚碇基础在施工期及运营期内位移和转角的变化,可知深度效应对锚碇基础承载力的增强作用十分明显。     

空气幕辅助沉井下沉施工工艺浅析

本文结合了马鞍山长江公路大桥北锚碇沉井下沉施工,简要的分析了利用空气幕辅助大型沉井下沉的施工工艺。     

沉井基础降排水下沉施工技术应用

随着国内经济发展及设计施工技术的不断提高，沉井基础施工在大型桥梁工程尤其是大型桥梁基础中应用广泛，本文结合泰州大桥北锚碇沉井基础的工程实例，对降排水下沉施工技术进行介绍，并以确保附近长江大堤的沉降安全为目标，取得了较好的施工效果，于类似工程具有一定的推广和应用价值。     

锚碇沉井基础施工期安全监控技术

针对泰州大桥南锚沉井基础的结构特点和施工方法,设计了施工安全监控方案。施工期监测成果分析表明:沉井下沉初期沉井底部刃脚附近水平方向的拉应力较大,将此项物理量作为下沉的控制指标,有效指导了沉井施工;侧壁土压力分布随入土深度呈先增加后减小规律。     

鹦鹉洲大桥北锚碇运营期变形预测及控制措施

对于大跨径悬索桥的锚碇基础而言，在锚索力的作用下易产生较大的侧向位移，若此位移值过大，将影响悬索桥的运营安全，因此需要准确地对其进行预测分析。采用三维有限差分软件FLAC”建立鹦鹉洲大桥北锚碇基础的整体计算模型，计算运营加载后沉井基础的受力状态，预测锚碇基础的最终工后变形量，分析地基土水平抗力的分布规律。并对被动区土体加固参数（加固宽度、加固深度）对沉井及其周土的位移控制作用进行对比分析．得到了一些对实际工程有益的结论。     

大型深水沉井基础设计

泰州大桥采用主跨为1080m三塔两跨悬索桥,中塔位于主江中心。通过对沉井基础和高桩承台钻孔桩基础等多项基础方案的比选,考虑到沉井结构受力明确、刚度大、工序简单,经济性高等优点,中塔基础最终选用沉井基础。根据塔柱底的构造要求,受力要求,沉井采用58m×44m四角倒圆的矩形沉井,沉井总高76m。为了能在深水中顺利施工,沉井下部为钢壳混凝土结构,上部为钢筋混凝土结构。文中介绍了泰州大桥水中沉井的结构构造、施工方法、方案比较以及沉井的设计特点,为类似工程起到很好的借鉴作用。     

泰州大桥深水沉井基础设计

泰州大桥采用主跨为1080m三塔两跨悬索桥,中塔位于主江中心。通过对沉井基础和高桩承台钻孔桩基础等多项基础方案的比选,考虑到沉井结构受力明确、刚度大、工序简单,经济性高等优点,中塔基础最终选用沉井基础。根据塔柱底的构造要求,受力要求,沉井采用58m×44m四角倒圆的矩形沉井,沉井总高76m。为了能在深水中顺利施工,沉井下部为钢壳混凝土结构,上部为钢筋混凝土结构。文中介绍了泰州大桥水中沉井的结构构造、施工方法、方案比较以及沉井的设计特点,为类似工程起到很好的借鉴作用。     

沉井工程质量通病及施工过程控制

沉井施工是修筑深基础和地下构筑物的一种施工技术。其常见质量通病形式有:沉井偏斜、沉井停沉、沉井突沉、沉井超沉或欠沉、沉井干封底及沉井水下混凝土封底的一般故障等。本文分析了这几项常见质量通病的现象、产生的原因,重点阐述了预防措施。     

Taizhou Yangtze River Bridge—the first kilometer level three-pylon two-span suspension bridge in the world

Taizhou Bridge, located at the middle of Jiangsu Province, connecting City Taizhou and City Zhenjiang, was started in Dec. 2007. The bridge is the first kilometer-level three span suspension bridges in the world. The bridge adopts longitudinal herringbone shape steel middle pylon for the first time in the world. The foundation of the middle tower is the deepest underwater caisson in soil on earth. A great many of technical innovations are carried out to construct such a great project, such as the design techniques of the three-pylon suspension bridge, the precisely locating and bottom-sealing techniques of the large scale caisson foundation, the manufacture, combination techniques of steel and concrete in the middle tower, the welding of extra thick steel plate, the manufacture and control techniques of abnormal sections of the middle tower and so on.     

Research on subsidence method aided by water injection and its engineering application for the north anchor of Taizhou Bridge

The north anchorage caisson of TaizhouBridge encountered some difficulties during the sinking process for the large sidewall frictional resistances. To solve this problem, a new concept and method of called subsidence method aided by water injection is proposed.Numeral analysis is adopted to simulate and the effects of this method for the north anchor of TaizhouBridge, which confirmed the feasibility and validity. Finally, the method is applied to the north anchor caisson during the caisson sinking procedure and helpsthe caisson sinkand embedto the designed position smoothly.     

Vibration mechanism research of large scale and deep water caisson

According to the construction method of Taizhou Bridge, numerical simulation is conducted to analyze the vibration of caisson under wind and water flows to determine the main factors of the caisson vibration. Meanwhile, the localization system of caissons and anchors of Taizhou Bridge is modeled in order to summarize the vibration mechanism of caissons under deep-water and jet-flow condition, and further pertinent vibration-control measures are proposed. The obtained results are well verified in engineer practice, and consequently the safety risk of positioning the caisson during is reduced.     

Technical research on control of caisson construction for the middle tower foundation of Taizhou Bridge

The real-time informational monitoring system is adopted in the construction of middle tower foundation of Taizhou Bridge for the first time. The geometric state of the caisson, the stress of upstream and downstream anchorage cables, underwater topography, the drag forces of the caisson cutting edge and frictional resistances of the sidewall etc. are monitored in real time. According to the synthesized data analysis and decision-making system, the spatial states of the caisson are adjusted in time to locate and embed the deep water caisson precisely. The offset errors of the caisson are less than 30cm and the vertical errors is 1/363 at the final stage. The control technology for the construction of large caisson under deep water is concluded and would be helpful to the construction of bridge foundation in the future.     

A Study of the system control model of caisson dewatering of the north anchorage of Taizhou Bridge

A caisson foundation is applied to the north anchorage of Taizhou Yangtze River Highway Bridge of which the initial caisson sinking requires dewatering. Since the caisson foundation is quite close to nearby buildings, a system control model is established with source (sink) distribution and intensity being the object function, minimum requirements of settlement and deformation of surroundings caused by dewatering and dynamic water levels during different working procedures being constraints, and the design parameter of pumping wells being the variable, as so to lower the jeopardizing of surrounding buildings, which provides a new method for active control over settlement during dewatering. Such a method of dewatering based on system control model should be of significance for similar projects involving dewatering.