为了深入研究在不同施工工序下基坑开挖对基坑围护结构的内力和位移及周边环境的影响,运用岩土有限元软件Midas GTS分别模拟了广州某采用桩-锚索支护的高层建筑基坑在不同施工工序下的开挖过程,以及在进行底板施工时不对称堆载对基坑的影响,从而得到了基坑围护结构内力、变形及地表沉降的分布规律。计算分析结果表明:不合理的施工工序对基坑围护结构的内力和位移及地表沉降产生了较大影响,尤其是围护结构水平位移及地表沉降,这使得基坑的稳定性处于不利的状态;该基坑在锚索及时发挥作用比不及时发挥情况下,桩体最大弯矩减少率≥41.77%,地表沉降减少率≥32.75%;基坑底部不均匀堆载使得左、右侧桩体最大弯矩相差＞5%,桩体水平位移相差＞10%。研究结果将有助于提高深基坑设计水平,为类似工程的设计、施工和研究提供必要的参考。

In order to study the influence of excavation on the internal force and deformation of retaining structures and the surrounding environment under different construction procedures, we employed Midas GTS to simulate the excavation process of deep foundation pit with different construction procedures. A deep foundation pit supported by pile-anchor was taken as case study. We also simulated the influence of unbalanced heaped load on the foundation pit during the construction of base plate, and obtained the internal force and deformation of retaining structure and the ground subsidence. Results show that the horizontal displacement of retaining structure and the ground subsidence in particular were largely affected by unreasonable construction procedure, which is unfavorable for the stability of foundation pit. With timely anchor support, the maximum bending moment of pile decreased at least 41.77% compared with that in the absence of anchor support, ground subsidence reduced by 32.75% at least; unbalanced heaped load on the foundation pit led to more than 5% difference in the maximum moment and over 10% in the horizontal displacement of left and right piles. The research result will be helpful to the design of deep foundation pit, and offers reference for the design, construction and research of similar engineering.