Large-scale 3D seismic response analysis considering soil liquefaction in an urban area using the supercomputer “Fugaku”

抄録

With the development of high-performance computing finite element method (HPC-FEM), it is becoming possible to perform 3D seismic response analysis using large-scale analytical models that faithfully reproduce the geometry of the ground and buildings. On the other hand, 2D analyses or 3D models with simplified geometry have been the mainstream in seismic design in Japan due to the difficulty of applying HPC technology with sequential calculation codes and creating 3D ground meshes with complex geometry. For the purpose of using HPC-FEM in practice, we have developed an HPC-FEM program that incorporates constitutive laws for soil and liquefaction, which are commonly used in seismic design in Japan. This program extends the large-scale nonlinear finite element method program STRIKE (Ichimura et al., 2022). This extended program showed high scalability on the supercomputer

Fugaku and enabled the automatic creation of meshes with tetrahedral elements for complex geometries (Fujita et al., 2018). We did the seismic response analysis of a 1.4 × 1.3 km urban basin geometry. We used 12,288 CPU cores on Fugaku to perform the analysis of a highly detailed FEM model with 230 million DOF and 5,000 time steps. The analysis took approximately 48 hours. The results were compared with those of previous studies conducted in the same area with a voxel model of simplified ground geometry. The results of both analyses were consistent, verifying the developed program. In addition, the response near the formation boundary was reasonable compared to the results of the voxel model. These findings suggest potential superiority and usefulness of the developed 3D HPC-FEM program.