基坑开挖过程中邻近建筑群地表沉降特征研究

    Surface settlement characteristics of adjacent building groups during excavation

    • 摘要: 为揭示桩基建筑群的地表沉降规律,得到基坑外桩基建筑群的地表沉降特性曲线,基于PLAXIS 3D有限元软件,以天津地铁4号线区间车站基坑开挖工程为背景,系统分析基坑开挖过程中邻近建筑群区域地表沉分布特征,对比研究基坑周围有建筑群区域(浅基础、桩基础)与无建筑群区域的地表沉降差异,探讨建筑群位置及基础形式(桩基础、浅基础)对地表沉降的影响规律,提出桩基建筑群影响下的基坑外地表沉降曲线及影响分区。研究结果表明:基坑开挖过程中,地表沉降呈“V”字型分布,临近建筑群存在可一定程度减小地表沉降;桩基础通过增强周边地层强度,对地表沉降进行有效的限制,体现协同防护效应;根据地表沉降曲线,可将基坑外地表划分为Ⅰ级、Ⅱ级和Ⅲ级沉降区域。研究成果为复杂环境下邻近高层建筑群的基坑开挖工程提供了系统的风险评估方法,可指导施工中针对性优化支护设计,对保障周边建筑安全、提升基坑工程安全性具有重要参考价值。

       

      Abstract: To clarify the surface settlement characteristics induced by pile foundation building groups and to obtain the surface settlement profiles in the areas outside the foundation pit under their influence, this study employs the PLAXIS 3D finite element software, with the excavation of a interval station pit on the Line 4 of the Tianjin Metro as the engineering background. A systematic analysis is conducted on the spatial distribution of surface settlements in the vicinity of the building groups during the excavation process. By comparing the surface settlement behaviors in zones with and without building groups (including shallow foundations and pile foundations), the influence of building location and foundation type (shallow foundation or pile foundation) on the evolution of surface settlements is investigated. Based on these findings, the surface settlement curves and influence zones beyond the foundation pit affected by pile foundation building groups are proposed. The results indicate that the surface settlement during foundation pit excavation exhibits a typical "V"-shaped distribution; the presence of adjacent building groups can partially mitigate the surface settlement. Pile foundations, through the enhancement of surrounding soil stiffness and strength, effectively constrain surface settlements, demonstrating a synergistic protective effect. According to the surface settlement curves, the area outside the foundation pit is classified into three settlement zones: Zone Ⅰ, Zone Ⅱ, and Zone Ⅲ. This study provides a systematic method for settlement prediction and risk assessment in foundation pit excavations adjacent to high-rise building groups in complex environments. The findings offer a theoretical guidance for the optimization of support design during construction, and thus have significant reference value for ensuring the safety of surrounding structures and improving the overall safety of foundation pit engineering.

       

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