Three-dimensional Large-scale Marine Seismic Response Analysis Based on the Unified Computational Framework of Fluid-solid Interaction−A Case Study of Tokyo Bay
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摘要: 海域场地地震响应分析是确定海洋工程结构抗震设计地震动输入的重要环节。然而,针对海水、饱和土、基岩之间的流固耦合分析,目前一般通过对3种介质方程进行离散,然后整体求解或分区耦合求解的方式进行,过程复杂而低效。因此,大规模海域场地地震反应分析仍是一个挑战性问题。本文基于流固耦合统一计算框架求解海域近场波动问题,采用透射边界模拟无限域,通过将海水和基岩视为孔隙率分别等于1和0的广义饱和多孔介质,使得海水、饱和土、基岩之间的相互耦合可在统一计算框架中实现,避免不同介质求解器之间的数据交换。采用集中质量显式有限元并行计算,不同进程之间采用MPI进行数据交换,提高计算效率;采用逐元技术,按单元类别存储单元刚度,大大节省了内存,便于大规模计算。通过自编程,输入界面高程数据和材料参数,实现建模-自由场-三维地震动模拟全流程自动化。以东京湾为例,使用该方法和程序在超级计算机上模拟SV波垂直入射时的地震响应,证实了该方法用于三维大规模海域地震波场模拟的高效性和可行性。Abstract: The seismic response analysis of marine sites plays an important role in determining the ground motion input for the seismic design of marine engineering structures. However, for the fluid-solid coupling analysis between seawater, saturated soil, and bedrock, the three media equations are generally discretized, and then the overall solution or partition coupling solution is performed, which is complex and inefficient. Therefore, the seismic response analysis of large-scale marine sites is difficult at present. In this paper, an efficient unified approach is proposed to solve the near-field seismoacoustic scattering problem, and the influence of the infinite domain is simulated by the transmitting boundary. Seawater and dry bedrock are considered as generalized saturated porous media with porosity equals to one and zero respectively, and the coupling between seawater, saturated seabed and dry bedrock can be analyzed in the unified framework of generalized saturated porous media and avoid interaction between different solvers. In order to improve the computing efficiency, the concentrated mass explicit finite element parallel computing is adopted, and MPI is used for data exchange between different processes. Through self-programming, users only need to input the interface elevation data and material parameters to realize the whole process automatic operation of modeling-free field-3D ground motion simulation. Finally, this method and program is used to simulate the seismic response of SV waves vertically incident on the Tokyo Bay area on high performance computer. The numerical results confirm the high efficiency and feasibility of the method for 3D large-scale sea seismic wave field simulation.
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图 5 Koketsu等(2009)确定的第一界面深度
Figure 5. The first interface depth determined by Koketsu et al.(2009)
表 1 东京湾材料参数(Koketsu 等, 2009)
Table 1. Parameters of materials used in Tokyo bay (Koketsu et al., 2009)
材料 孔隙率/β μ0 ρs /kg·m−3 Ρw/kg·m−3 ν G /GPa Ew /GPa M /GPa α k0/μm2 海水 1 0 0 1000 0.020 0 2.25 2.25 1 1 基岩1 0 0 1850 0 0.437 0.666 0 — 0 0 基岩2 0 0 2080 0 0.395 2.080 0 — 0 0 -
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