大型陆地锚碇沉井下沉结构受力分析及关键技术
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摘要
五峰山长江大桥是世界上第一座跨度超过千米的公铁合建钢桁梁悬索桥,其北锚碇沉井长100.7 m、宽72.1 m、高56 m,具有平面尺寸大、入土深、重量大、结构柔等特点。沉井施工过程中结构受力复杂,目前并无针对该类超大沉井施工期受力特性研究的先例。为了防止常规"锅底式"方式开挖下沉时因沉井跨度过大造成结构开裂,提出"核心土预留"滞后开挖方式,在沉井中间部位形成一定范围的支撑,减小沉井受力跨度,有效的改善了沉井结构受力、确保了结构安全,并通过MIDAS FEA有限元软件模拟计算与应力监测对该开挖方式进行分析探究,验证了此方法的可行性。
The Wufengshan Yangtze River Bridge is the world's first steel truss suspension bridge with a span of more than1 000 kilometers. Its north anchorage is 100.7 m long, 72.1 m wide, and 56 m high. It has the characteristics of large plane size,deep soil depth, large weight, and soft structure, etc. The structure of caisson construction is complex, and there is no precedent for the study of the stress characteristics of caisson construction period. In order to prevent the structure cracking caused by the large span of the caisson due to the sinking of the conventional "pot bottom type" excavation, we proposed a delayed excavation method of "core soil reservation" and forms a certain range of support in the middle of the caisson, which reduces the stress span of the caisson, effectively improves the stress of the caisson structure and ensures the safety of the structure. This method is proved to be feasible by means of MIDAS FEA software simulation and stress monitoring for sinking construction.
The Wufengshan Yangtze River Bridge is the world's first steel truss suspension bridge with a span of more than1 000 kilometers. Its north anchorage is 100.7 m long, 72.1 m wide, and 56 m high. It has the characteristics of large plane size,deep soil depth, large weight, and soft structure, etc. The structure of caisson construction is complex, and there is no precedent for the study of the stress characteristics of caisson construction period. In order to prevent the structure cracking caused by the large span of the caisson due to the sinking of the conventional "pot bottom type" excavation, we proposed a delayed excavation method of "core soil reservation" and forms a certain range of support in the middle of the caisson, which reduces the stress span of the caisson, effectively improves the stress of the caisson structure and ensures the safety of the structure. This method is proved to be feasible by means of MIDAS FEA software simulation and stress monitoring for sinking construction.
引文
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[8] JTGD 63—2007,公路桥涵地基与基础设计规范[S].JTGD 63—2007, Code for design of ground base and foundation of highway bridges and culverts[S].
[2]赵有明,田欣,牛亚洲,等.南京长江第四大桥北锚碇沉井基础施工关键技术[J].桥梁建设,2009(S1):62-65.ZHAO You-ming, TIAN Xin, NIU Ya-zhou, et al. Key Techniques for construction of north anchorage caisson foundation of the Fourth Nanjing Changjiang River Bridge[J]. Bridge Construction, 2009(S1):62-65.
[3]张凤祥.沉井沉箱设计施工及实例[M].北京:中国建筑工业出版社,2011.ZHANG Feng-xiang. Design and construction of open caisson[M].Beijing:China Architecture&Building Press, 2011.
[4]穆保岗,朱建民,龚维明,等.悬索桥大型沉井排水下沉控制的关键问题分析[J].中国公路学报,2013(6):118-127.MU Bao-gang, ZHU Jian-min, GONG Wei-ming, et al. Key issues about drainage sinking control of large caissons in suspension bridge[J]. China Journal of Highway and Transport, 2013(6):118-127.
[5]蒋勋林.超大沉井排水下沉的安全控制研究[J].石家庄铁道大学学报:自然科学版,2014,27(S1):1-4.JIANG Xun-lin. Study on safety control of drainage sinking of super large caisson[J]. Journal of Shijiazhuang Tiedao University:Natural Science Edition, 2014, 27(S1):1-4.
[6]穆保岗,朱建民,牛亚洲.南京长江四桥北锚碇沉井监控方案及成果分析[J].岩土工程学报,2011,33(2):269-274.MU Bao-gang, ZHU Jian-min, NIU Ya-zhou. Monitoring and analysis of north anchorage caisson of Fourth Nanjing Yangtze River Bridgev[J]. Chinese Journal of Geotechnical Engineering, 2011,33(2):269-274.
[7]陶建山.泰州大桥南锚碇巨型沉井排水下沉施工技术[J].铁道工程学报,2009(1):63-66.TAO Jian-shan. Construction technology for draining-sinkage for south caisson anchorage to Taizhou Yangtze River Highway Bridge with large-sized sunk well[J]. Journal of Railway Engineering Society, 2009(1):63-66.
[8] JTGD 63—2007,公路桥涵地基与基础设计规范[S].JTGD 63—2007, Code for design of ground base and foundation of highway bridges and culverts[S].