Discrete-Element Method Simulations of the Seismic Response of Flexible Retaining Walls
Discrete-Element Method Simulations of the Seismic Response of Flexible Retaining Walls
复制标题
柔性挡土墙地震响应的离散元法模拟
DOI：
10.1061/(asce)gt.1943-5606.0002428
复制
发表时间：
2021
影响因子：
3.9
通讯作者：
El Shamy, Usama
中科院分区：
文献类型：
--
作者：
Sizkow, Saman Farzi;El Shamy, Usama
本文采用三维离散元法（DEM）对挡土墙的动力相互作用进行了模拟分析。土壤颗粒被视为刚性的球形颗粒，允许在接触点上彼此重叠。柔性板桩式挡土墙采用具有特定强度和刚度的平行胶合刚性球来模拟真实墙体的物理特性和刚度。由于计算的限制，采用了动态离心机测试的高级概念和标度定律来减小域的大小和模拟时间。此外，在模型的侧面采用了自由场边界，以防止传播波反射回装配并强制自由场运动。地震激励是通过代表基岩的基底墙引入系统的。分析了输入地震波的频率、振幅等不同特征对土-板桩体系动力响应的影响。此外，还收集了墙体侧推力、弯矩及其挠度的数据。研究发现，在地震激励过程中，侧土压力和弯矩均有所增大，且在大多数情况下，其最终残差值均明显大于初始静力作用时的残差值。同时观察到，在动荷载作用下，床单桩背后地面加速度的最大放大、墙体变形量以及床单桩承受的最大内力和弯矩水平受到输入运动频率和振幅的强烈影响。结果表明：当地加速度大于某一临界极限时，最大侧土压力基本保持不变；然而，即使地面加速度高于临界值，壁面上的最大动弯矩也会增加。
In this study, an analysis of soil–retaining wall dynamic interaction is conducted using three-dimensional discrete-element method (DEM) simulations. Soil grains are treated as rigid spherical particles that are allowed to overlap one another at contact points. The flexible sheetpile-type retaining wall is simulated using rigid balls glued together by parallel bonds with specific strength and stiffness to mimic the physical properties and stiffness of a real wall. Owing to computational limitations, the highg-level concept and scaling laws for dynamic centrifuge testing are utilized to decrease the domain size and simulation time. In addition, free-field boundaries are employed at the lateral sides of the model to prevent the reflections of the propagating waves back to the assembly and enforce free-field motion. Seismic excitation is introduced to the system through the base wall, which represents the bedrock. The effects of different characteristics of the input seismic wave, such as its frequency and amplitude, on the dynamic response of the soil–sheetpile system are analyzed. Furthermore, data on the lateral thrust and bending moment on the wall and its deflection are collected. It is found that the lateral earth pressure and bending moment increase during seismic excitation and the final residual values are, in most cases, considerably larger than the initial static ones. It is also observed that the maximum amplification of ground acceleration behind the sheetpile, the amount of wall deformation, and the maximum level of internal forces and moments the sheetpile experiences during dynamic loading are strongly affected by the frequency and amplitude of the input motion. The results show that for ground acceleration stronger than a critical limit, the maximum lateral earth pressure stays almost at a constant level. However, the maximum dynamic bending moment on the wall is found to increase even for ground accelerations higher than the critical value.