立体车库的基坑变形与周围土体位移分析

Analysis of pit deformation and displacement of surrounding soil in stereo garages

为了解超深小尺寸基坑开挖过程中围护结构和周围土体的变形规律,对杭州地区某个超深小尺寸立体车库基坑进行变形监测,并借助Plaxis有限元软件模拟,分析基坑开挖过程中围护结构变形和周围土体位移的变化规律。研究表明:基坑开挖引起地连墙侧向位移呈现“弓”型变形;测斜管1方向和测斜管2方向位移最大值分别为44mm和43mm,这表明内隔墙的空间效应造成基坑长边中心与短边中心位移相当,且对基坑变形有抑制作用;地表沉降最大值点所在位置与深大基坑相比,地表沉降最大值点位于距离围护结构约0.2倍的开挖深度,这表明地表沉降最大值点更靠近围护结构;对于在复合型模式下的围护结构,坑外土体位移场可以由位移值进行分区。与其他基坑工程数据的对比结果发现,小尺寸基坑抵抗变形效果更好,这表明超深小尺寸立体车库的基坑变形小,在城市市中心区域具有潜在的应用前景。

In order to understand the deformation law of retaining structure and surrounding soil during the excavation of ultra-deep and small-sized foundation pits,our study monitored the deformation of a given ultra-deep and small-sized stereo garage in Hangzhou,simulated with the help of Plaxis finite element software and analyzed the variation law of the deformation of retaining structure and displacement of surrounding soil during the excavation of foundation pit.The results show that the lateral displacement of diaphragm wall induced by the excavation of foundation pit presents a“bow-shaped”deformation.The maximum displacements along inclinometer 1and inclinometer 2are 44mm and 43mm respectively.This indicates that the spatial effect of the diaphragm wall makes the center of the long side of the pit equivalent to that of the short side,and plays an inhibiting role in the deformation of the pit;The location of the point with maximum surface settlement is compared with that of the deep and large pit,and the point with maximum surface settlement is located at about 0.2times the excavation depth away from the retaining structure.This indicates that the point with maximum surface settlement is closer to the retaining structure.For the retaining structure under the compound mode,the soil displacement field outside the pit can be zoned by displacement value;compared with the engineering data of other pits,small-sized foundation pits can better resist deformation,which shows that the deformation of the foundation pit of the ultra-deep and small-sized stereo garage is small,and it has a potential application prospect in downtown areas in the city.