软土地区超大规模深基坑设计与变形监测分析

Design and Deformation Monitoring of a Large Deep Foundation Pit in Soft Soil Area

于家堡深基坑位于天津软土地区,整体开挖规模达10×104,m2.依据监测数据,详细分析了基坑施工各阶段的围护桩身变形、土体侧移以及坑外地表沉降的变形及发展规律.分析结果显示,该基坑支撑刚度和施加位置对排桩变形模式起决定性作用,桩身最终仍呈'倒三角'悬臂排桩的线性变化规律,最大位移仍出现在桩顶.第2步开挖对该基坑围护结构影响很小,围护桩及土体变形均主要发生在第1步开挖.监测数据分析揭示了该超大规模深基坑的实际状态,可为类似超大规模深基坑工程的围护结构设计和科学施工提供参考.

Yujiabao deep foundation pit,whose excavation scale reaches to 10＆#215;104,m2,is located in Tianjin soft soil area. Based on the actual monitoring data of the deformation of row pile retaining structures,the deformation rules of retaining structures,soil and the ground surface settlement outside pit at each construction stage of deep foundation pit are analyzed. The results indicate that the stiffness and applying position of braces play a decisive role on the de-formation modes of piles,the curve of retaining piles still changes linearly like an inverted triangle,the maximum horizontal displacement happens at the top of the pit. The second step in the excavation have a small influence on the retaining structure. The deformation of retaining structures and soils mainly occurs in the first step excavation. The deformation behavior of this huge deep foundation pit can provide the reference for the optimization design and scien-tific construction of similar deep foundation pits.