对某深基坑开挖全过程中围护桩的水平位移进行了实测,由于水平支撑提供的支撑刚度不同,不同位置处的围护桩可产生不同的水平位移分布模式,且最大水平位移值也存在明显差别。通过建立考虑土体小应变的有限元模型,针对4种典型同护结构变形模式引起的坑外深层土体位移场变化特点进行分析,结果表明:即使围护结构最大水平位移相同,由于侧移分布模式不同,基坑外地表和深层土体的竖向及水平位移场均可存在较大差别,从而可能对环境产生不同程度的影响。围护结构在内凸型和复合型模式下,坑外深层土体竖向变形可分为阳槽形沉降区、三角形过渡区和隆起区,而深层土体水平位移场可分为弓形变形区、变形过渡区以及悬臂形变形区;悬臂型模式下坑外深层土体竖向位移场只存在三角形变形区和隆起区,而水平位移场则全部呈悬臂形;踢脚型模式下的竖向位移和水平位移影响范围均为最大。在实际工程中除控制围护结构最大变形值外,尚应根据周围环境特点合理控制围护结构变形模式,并尽可能避免出现踢脚模式变形。
The horizontal displacements of the retaining piles are monitored through the whole process of a deep excavation project. It is found that, due to the differences of horizontal bracing stiffness, the deformation modes of the retaining piles at different locations are different, and the maximum horizontal displacements also have significant differences. Through FEM modeling, the characteristics of the displacement fields caused by four deformation modes of retaining walls are analyzed. The results show that under the situations of different deformation modes of retaining structures with the same maximum horizontal displacement, the displacement fields of soils outside the excavation can be considerably different, and therefore the impacts on environment may vary greatly. In practical projects, besides controlling the maximum horizontal displacements of the retaining structures, the deformation mode of the retaining structures should be optimized according to the surrounding environment, and their kick-in deformation should be avoided.