复杂环境下地铁深基坑变形行为的实测研究

本文通过对上海软土地区开挖深度为15.5m的多支撑基坑的现场实测,发现与世界范围其它工程实例相比,本基坑的墙体侧移和地表沉降是非常小,空间效应不明显,其原因是基于时空效应的分层分小块的快挖快撑、坑内注浆加固以及积极的支撑预加轴力等措施的应用。同时通过土体体积的变化量和平方根时间方法分析在中板养护期间的土体随时间变形,指出在开挖期间基坑变形不仅仅与土蠕变相关,土体的固结也对变形产生了相当的影响。

Study on the deformation of a deep metro excavation under complex environment

A 15.5-m-deep multi-strutted metro excavation in Shanghai soft clays was monitored. It was found that relatively small wall deflections and ground settlements were measured as compared with similar case histories worldwide, and no significant space effect existed. The reason was probably because of the use of short excavation section, application of compaction grouting for improving ground conditions and the use of active pre-stress steel struts based on the theory of time-space effect. Based on soil volume change and square root time method, time-dependant soil deformation was studied during curing period of middle-slab concrete. It was pointed out that the settlement was attributed to the primary consolidation as well as creep effects.