深厚砂层深挖圆形竖井施工数值模拟及实测分析

湛江湾跨海盾构隧道竖井开挖深度大,地处深厚砂层,其围护结构受力条件复杂。根据该工程所处地质环境和围护结构设计特点,采用地层结构有限元增量法,详细模拟盾构竖井的施工过程,重点分析竖井围护结构的水平位移及受力规律,并与实测进行对比,得出以下结论:由于所处地层较软和加固土体的作用,导致始发井连续墙后靠背侧水平位移随深度呈横向“W”型分布,接收井各侧面水平位移呈横向“V”型分布;计算和实测均表明接收井施工过程的高风险工况为开挖至第5层和第6层处;接收井的水平位移及钢筋应力计算值与实测结果趋势较吻合。其分析方法和监测成果可为今后沿海深厚砂层深挖盾构竖井的设计与施工提供参考。

Numerical Simulation and Field Monitoring Analysis on Structural Construction of Deep Round Thick Sand Shaft

The working shaft of shield tunnel in Zhanjiang Bay has a large depth of excavation,in which the deep sand,the stress conditions of envelope are complex.According to the geological conditions and the features of envelope,the finite element incremental method was used for the formation to calculate the displacement and internal force for envelope during process of shield shaft construction.The deformation law and force characteristics of envelope were analyzed,and compared with the field monitoring,drawing the following conclusions:Because of the soft stratum and strengthening the role of soil,the horizontal displacement distribution of diaphragm wall at back side of starting shaft was transversal "W" type;The horizontal displacement distribution of diaphragm wall at different sides of arriving shaft was transversal "V" type;It was the most dangerous working conditions of arriving shaft when constructed to the fifth and sixth floor,which was revealed by both calculated and measured;The calculated horizontal displacement and reinforced stress of arriving shaft were agreed well to measured on the trend.A reference will be provided according its analytical methods and monitoring results for the future of coastal sand digging deep shafts design and construction.