软土地基上海堤变形与失稳的离心模型试验与数值分析

Centrifugal model test and numerical analysis of deformation and stability of seawall on soft clay

软土地基上海堤的沉降及稳定性是围垦海堤工程的关键问题。针对海堤工程开展离心机模型试验,分别通过变加速度法及恒加速度法模拟海堤填筑过程和竣工后稳定运行过程,得到了海堤施工期及工后沉降变化规律,并通过PIV技术观察海堤的破坏模式;在此基础上,采用Geo Studio软件分别基于总应力及有效应力分析法,分析了海堤施工期及竣工后稳定运行期海堤的整体稳定性随时间变化规律。物理和数值模拟结果表明,离心模型试验能一定程度上模拟海堤的变形及失稳情况,且与数值分析结果吻合较好。海堤施工期瞬时失稳的滑裂面贯穿软土地基,并使海堤滑体发生了超过1 m的瞬时沉降。海堤填筑完成后地基超静孔隙水压力逐渐消散、海堤稳定性安全系数随时间不断提高。海堤竖向和水平位移最大值分别位于堤轴线处及坡脚处。

Deformation and stability of the seawall on soft clay are the key problems for reclamation engineering. Centrifugal model test is carried out to obtain the soft clay settlements, where the variable acceleration method and constant acceleration method are applied to simulate the construction process and operating phase, respectively. Particle image velocimetry（PIV） technique is also introduced to capture the potential failure mode of seawall. Further, based on the total stress and effective stress analysis methods, the changes of global stability with time are analyzed by using Geo Studio software in both the construction process and operating phrase. Physical and numerical simulation results show that the centrifugal model test is able to reflect the deformation and stability behaviors of the seawall to a certain extent; and its data is in good agreement with that obtained by numerical simulation. The sliding surface of the seawall passes through the soft clay, leading to an immediate settlement of more than 1 m. In addition, the safety factor of global stability increases gradually with time after the seawall construction due to the dissipation of excess pore pressure. The maximum vertical and horizontal displacements are located at the axis and the toe of the seawall, respectively.