Design, Construction, and Installation of a Floating Caisson Used as a Bridge Pier
Design, Construction, and Installation of a Floating Caisson Used as a Bridge Pier
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DOI：
10.1061/(asce)0733-950x(2006)132:3(143
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发表时间：
2006-05
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影响因子：
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通讯作者：
S. Chakrabarti;P. Chakrabarti;M. Krishna
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文献类型：
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作者：
S. Chakrabarti;P. Chakrabarti;M. Krishna
河流上的悬索桥通常支撑在一个结构上，该结构安装在靠近两岸的河底上的大型混凝土桥墩上。由于其庞大的规模，桥墩是通过在现场浇注混凝土在浮动的位置。在施工期间，浮式沉箱系泊到位，以承受现场可能普遍存在的任何环境水流和波浪。由于沉箱的吃水深度在施工期间会发生变化，因此系泊系统必须能够在所有这些吃水深度下保持沉箱。一旦施工顺序达到要求的高度，沉箱被压载到河底，随后在进一步压载过程中渗透土壤到其所需的深度。桥墩及其系泊系统的设计和施工带来了若干技术挑战。本文介绍了在西雅图附近的塔科马海峡的一座新桥的沉箱系统设计中遇到的这些挑战。该设计过程包括以浅吃水将沉箱从码头拖至现场、设计和安装系泊系统、在适当位置建造沉箱以及最终触地和贯入土壤。狭窄处的水流非常高，这给施工顺序带来了特别的挑战。一些关键领域的相关设计和解决方案的技术突出显示。应注意的是，桥梁沉箱及其系泊系统的尺寸与暴露于恶劣环境的典型海上结构的尺寸具有相似的数量级。
A suspension bridge over a river is generally supported on a structure mounted on large concrete piers placed on the river bottom near the two banks. Because of its massive size the piers are built by pouring concrete at site in a floating position. During this construction period, the floating caissons are moored in place to withstand any environmental currents and waves, which may be prevalent at the site. Since the draft of the caisson changes during construction, the mooring system must be capable of holding the caisson at all these drafts. Once the construction sequence reaches the required height, the caisson is ballasted down to rest on the river bottom and subsequently during further ballasting penetrates the soil to its desired depth. The design and construction of the piers in place and their mooring system provides several technical challenges. This paper describes these challenges experienced in the design of a caisson system for a new bridge at Tacoma Narrows, close to Seattle. This design process included towing the caissons at a shallow draft from the dock to the site, design and installation of the mooring system, construction of the caissons in place, and final touchdown and penetration to soil. The current at the Narrows was extremely high, which gave particular challenges in the construction sequence. Some of the critical areas of the associated design and their solution techniques are highlighted. It should be noted that the dimensions of the bridge caissons and their mooring system are of similar order of magnitude as typical offshore structures exposed to severe environment.