综合管廊深基坑支护桩长优化分析

Optimum Analysis on Supporting Pile Length of Deep Foundation Pit for Utility Tunnel

综合管廊属线性工程,明挖施工的基坑呈“窄长”型特点,与工业与民用建筑大面积方形或圆形的基坑有较大的不同,管廊基坑在两排围护桩共同约束下中间土体稳定性得以提高,若采用现行规范设计偏保守。基于平潭综合管廊基坑实例,采用有限元软件模拟地下综合管廊在5种不同桩长支护下的基坑变形特征,得到最优的桩长(19.7m)比原设计桩长(23.7m)较短;通过现场的实际监测表明,优化后的桩长能满足基坑变形及稳定性的要求。通过对管廊基坑支护桩长的优化,不仅节约了造价,也加快了进度。该优化思路可供相关工程借鉴。

The utility tunnel belongs to the linear engineering.The excavated foundation pit is narrow and long,which is quite different from the large area of square or circular foundation pit in industrial and civil buildings.The stability of the intermediate soil of the foundation pit of utility tunnel is improved under the joint restraint of two rows of retaining piles.If the current code is adopted,its design is conservative.Based on the foundation pit of Pingtan Utility Tunnel,this paper simulates the deformation characteristics of the foundation pit of the underground utility tunnel under the support of five different pile lengths by using finite element software,and obtains that the optimal pile length(19.7 m)shorter than the original design pile length(23.7 m).The field monitoring shows that the optimized pile length can meet the requirements of the deformation and stability of the foundation pit.The optimization of the support pile length of foundation pit for utility tunnel not only saves the cost,but also speeds up the schedule.This optimization idea can be referred for the similar projects.