某深基坑开挖过程的三维数值分析

本文运用有限差分软件FLAC^3D对某地铁车站基坑开挖与支护进行了模拟计算，分析了基坑开挖过程中围护结构变形、坑底隆起、地表沉降和相邻高架桥桩体的变形规律。结果表明：在深厚的粉细砂层中，地连墙变形有明显的“踢脚”现象；基坑由于开挖卸荷会导致明显的基坑隆起；坑外地表沉降影响范围主要在开挖深度的一倍范围内；基坑开挖也会引起相邻高架桥桩的侧向变形，最大侧移发生在开挖面附近。计算得到的地连墙和高架桥桩的侧向变形规律与已有文献的实测沉降规律基本一致，验证了计算结果的正确性。分析结果为类似工程设计与施工提供了有益参考。

THREE-DIMENSIONAL NUMERICAL ANALYSIS OF THE FOUNDATION PIT

The finite-difference software FLAC^3D was employed to simulate excavation and support of the foundation pit. Deformation characteristics of the enclosure structure, heave of base, ground settlement and adjacent viaduct pile were analyzed in different excavation stage. The numerical results indicate that there is the significant ‘kick-out＇ phenomenon in deep silty fine sand layer; Obvious heave of base is caused by excavation unloading; The influence range is on one time excavation depth; The excavation of the foundation pit makes the adjacent viaduct pile generate the lateral movement, and the largest lateral displacement disappears nearby the excavation face. The lateral displacement curves of the underground diaphragm wall and viaduct pile are basically consistent with the field ones from the existing literatures, so it is proved that the results are correct. The numerical results also provide a useful reference for the design and construction of similar projects.