软土中38m深基坑开挖的变形特征
摘 要
随着经济发展，对基础设施的需求也在不断增长。为了满足这种需求，上海已经开展了大量的深基坑工程。本文讨论的内容是：上海软土38米深深基坑多支护开挖的现场施工情况。该深基坑采用65 m深的地下连续墙做围护结构，并安装了测斜仪以及升沉和隆起标记，上面都安装了监测深基坑实时变化的仪器，以监测深基坑的数据。该项目提供了一个机会，用来研究挖掘过程中立柱和地下连续墙的升沉的现象。由于开挖的深度达38米，因此会引起显著的应力变化。通过布置的监测仪器观察到立柱和地下连续墙的最大升沉分别约为30mm和16mm。由此计算出柱的测量比dp/ H（升沉值/最终挖掘深度）小于0.1％，而地下连续墙的dp/ H约为0.04％。通过计算，柱和地下连续墙的最大变形小于1/500，该值未超过Bjerrum于1963年提出的限制范围，因此认为是合格的。这可能是因为仔细的施工、做了刚性支撑系统和采取了压实灌浆等方法，故该场地测得的墙体侧移和地面沉降小于上海，新加坡和台北的软粘土中的其他案例。
关键词：多支护开挖，软粘土，现场数据。
Deformation characteristics of a 38 m deep excavation in soft clay
ABSTRACT
To meet the increasing demand for underground space for economical development and infrastructural needs, more and more deep excavations have been constructed in Shanghai. In this paper, field performance of a 38 m deep multi- strutted excavation in Shanghai soft clay is reported. The deep excavation was retained by a 65 m deep diaphragm wall. In- clinometers as well as settlement and heave markers were installed to monitor the performance of the deep excavation. This project provides an unusual opportunity to study the differential heaves of center columns and diaphragm walls during exca- vation. Because of the significant stress relief resulting from the 38 m deep excavation, maximum heaves of the center col- umn and diaphragm wall panel were about 30 and 16 mm, respectively. The measured ratio dp/H (heave/final excavation depth) of column is less than 0.1% whereas the observed dp/H of the diaphragm wall panel is about 0.04%. The maximum distortion between the column and the diaphragm wall panel is smaller than 1/500, which is within the limit range proposed by Bjerrum in 1963. Owing to careful construction control, stiff strutting system, and compaction grouting, the measured lateral wall deflections and ground settlements at this site are generally smaller than other shallower excavations in soft clays in Shanghai, Singapore, and Taipei.
Key words：multistrutted excavations, soft clays, field data.
目 录
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