根式沉井基础力学分析与施工工艺

Mechanical Analysis and Construction Technology of Root Type Caisson Foundations

为分析根式沉井基础受力机理并总结其施工工艺,对马鞍山长江大桥江心洲Z1号、Z5号、Z9号桥墩基础开展相关研究。分别建立根式沉井在竖向荷载、水平荷载及荷载组合作用下的力学模型,结合经验公式,推导出该类基础竖向、水平承载力及结构变形等的分析方法。对Z5号桥墩基础B进行受力计算,将计算结果与实测结果进行对比得出:在井壁增加根键可有效提高沉井基础的承载力。通过工程实践,确定Z1号、Z5号、Z9号桥墩基础采用以压重为主的助沉方案,根键施工按自下向上的顺序逐层进行,对称顶进。

To analyze the mechanical mechanism and to summarize the construction technology of root type caisson foundations,the relevant study of the foundations for Piers No.Z1,Z5 and Z9 of Maanshan Changjiang River Bridge in the ait of the river was made.The mechanical models for the root type caisson foundations under the action of vertical load,horizontal load and load combination were respectively established and with reference to the empirical formulae,a set of the analysis methods for vertical,horizontal load bearing capacity and structural deformation of the type of the foundations was derived.The force conditions of the foundation B of Pier No.Z5 were calculated,the results of the calculation were compared to those of the measurement and it was concluded that the adding of root studs to the caisson walls could effectively increase the bearing capacity of the caisson.According to the construction practice,it was also determined that the foundations of Piers No.Z1,Z5 and Z9 should be sunk down mainly by weighing down the foundations.The construction of the root studs should be carried out in the sequence from the lower to the upper lift of the caisson by lift and should be jacked in symmetrically.