深开挖卸载条件下坑底群桩受力特性的有限元分析

大面积的深基坑坑底往往设置密集的工程桩,深开挖导致的土体卸荷回弹作用会对这些工程桩产生强烈的影响。采用ABAQUS软件建立平面有限元分析模型,对深开挖过程中坑底群桩的受力特性进行研究,确定桩顶抬升量、桩土相对位移、桩身轴力和桩侧摩阻力的分布。最后在开挖结束时对各工程桩重新加载,根据Q-s曲线来判断其抗压承载力和抗拔承载力。结果表明,工程桩的承载力与其在基坑平面中的位置有关。

FINITE ELEMENT ANALYSIS OF LOADING CHARACTERS OF GROUP PILES FOUNDATION DUE TO UNLOADING OF DEEP EXCAVATION

Large scale deep excavation is normally followed by construction of serried engineering piles inside the excavation zone,and unloading and rebound of soil induced by deep excavation have a great influence on those engineering piles. The mechanical characteristics of the pile groups in the bottom of foundation during the process of deep excavation were studied through building plane finite element model by ABAQUS software,and it was determined the lifting extent of pile block,pile-soil relative displacement,pile shaft force,and side friction of pile. Finally,each engineering pile was reloaded when excavation came to an end,then it was made judgments about their compressive bearing capacity and uplift bearing capacity according to the Q-s curve. The results showed that the bearing capacity of the engineering piles was related to their positions in the foundation excavation plane.