Challenges and Uncertainties Relating to Open Caissons
Challenges and Uncertainties Relating to Open Caissons
复制标题
与沉箱相关的挑战和不确定性
DOI：
--
复制
发表时间：
2012
期刊：
影响因子：
--
通讯作者：
K. E. Gaaver
中科院分区：
文献类型：
--
作者：
F. Abdrabbo;K. E. Gaaver
摘要沉井在岩土工程中有着广泛的应用。开口沉箱可用作深基础构件，绕过软弱土壤，在坚固的深层倾倒，并用于河流和海上建筑，以减少冲刷风险。露天沉箱也用于收集通过重力污水管网或来自下水道动力总管的污水。在这种应用中，开口沉箱的设计和施工需要详细的土壤调查计划。这样，就可以在充分了解主要底土条件的情况下制定沉井的设计和施工计划。工程技术和施工工艺是实现功能性沉箱的关键。根据施工阶段的密切观察，本研究提出了两个内径为20 m和10 m（65.6 ft和32.8 ft）的开口沉箱施工期间遇到的一些挑战。本文介绍了减轻施工困难的程序。满足设计和施工要求的场地勘探方案和控制措施是关键。在密实或非常密实的砂层中下沉沉井是有风险的。不正确的沉井下沉可能会导致额外的费用，延误施工，并损害附近的结构。在沉井的切割边缘附近、泥浆槽外部和/或明渠内部可使用空气/水喷射来向下驱动沉井。沉井周围的不对称作业可能导致沉箱倾斜。如果发生这种情况，应在恢复下沉过程之前立即纠正倾斜。沉箱开挖床上的细料清理不当，和/或水下混凝土浇筑不当，可能导致混凝土密封不良。该文件载有一系列实用指引，以协助有意使用沉井的人士，并与从业员分享良好的沉箱下沉方法。最后，本研究旨在了解遇到的困难，并预测未来的问题。
Abstract Open caissons are used for many geotechnical engineering applications. Open caissons may be used as deep foundation elements bypassing weak soils to tip in firm deeper strata, and in rivers and maritime construction to reduce the risk of scour. Open caissons are also used for collecting sewage water through gravity sewer pipe networks or from sewer force mains. In such applications, the design and construction of open caissons require a detailed soil investigation program. In this way, the design and construction plan of an open caisson can be developed with full knowledge of the prevailing subsoil conditions. The engineering and construction techniques are key factors to achieve functional caissons. Based on close observations during construction stages, the current study presents some challenges that were encountered during the construction of two open caissons of internal diameters 20 m and 10 m (65.6 ft and 32.8 ft). This paper describes the procedure followed to alleviate the construction difficulties encountered. Site exploration program and control measures required to satisfy design and construction requirements are crucial aspects. Sinking of open caissons in dense or very dense sands is risky. Incorrect sinking of open caissons may cause extra cost, delay in construction, and harm to nearby structures. Air/water jetting near the cutting edge of an open caisson, outside slurry trench, and/or inside open trench may be used to drive an open caisson downward. Unsymmetrical work around an open caisson may lead to tilting of the caisson. If this occurs, the tilt should be immediately corrected before resuming the sinking process. Improper cleaning of fine materials on the caisson’s excavation bed, and/or inappropriate pouring of underwater concrete may result in a defective concrete seal. The paper contains a series of practical guidelines to assist those intending to use open caissons, and shares good caisson sinking practice with practitioners. Finally, the study aims to understand the difficulties encountered and to anticipate future problems.