天津某深基坑工程施工监测及数值模拟分析

Construction monitoring and numerical simulation for a deep excavation in Tianjin

介绍了天津铜锣湾广场深基坑工程开挖实例。通过对深基坑开挖过程中的支护结构内力、坑周土体水平位移等的现场监测和数值模拟分析,讨论了基坑开挖过程中支护结构受力的特点及其对周围环境的影响,得到基坑周边土体水平位移的变化规律,为考虑施工因素的深基坑开挖及支护结构设计提供了依据。分析表明:土方开挖对基坑周围土体的影响范围约为两倍的开挖深度;开挖过程中土体及围护桩最大位移位置基本上都处于基坑开挖面附近;在基坑施工过程中,应该尽量减小无支撑暴露的时间,加快底板浇注,防止因土体流变而产生过大的位移;对于环梁支撑体系,如果支撑布置不规则,会造成受力不均,容易产生较大的弯矩值,会对环梁支护结构产生不利影响。

A test section was designated for a deep foundation pit for the Tianjin Causeway Bay Plaza. Bracing force and lateral displacement of soils were measured. Construction monitoring and numerical analysis were conducted to obtain the internal force of the bracing system and soil horizontal displacement. The characteristics of the internal force variation in the ring beam and the influence on the environment are discussed. The results of field measurement and numerical simulation indicate that the range of soil influenced by the excavation is about two times of the excavation depth and that the maximum soil displacement for a braced excavation usually occurs near the excavation surface. The analysis results also show that the reinforced concrete base slab should be poured promptly to reduce pit exposure time. For ring beam bracing system, irregular bracing arrangement may cause uneven force and large bending moment that in turn affects the ring beam bracing system.