PM4Sand-Based Nonlinear Constitutive Modeling of Sand Behavior under Seismic Loading

Abstract

This paper presents an analytical review of nonlinear constitutive modeling of granular soils under seismic loading with emphasis on the PM4Sand model. The revised manuscript addresses a central problem in the original draft: the earlier version was written with the rhetoric of an original numerical study, while it did not report a reproducible simulation program, calibrated datasets, or quantitative results. In the present version, the study is explicitly reframed as a structured literature-based review and engineering workflow. The paper first clarifies the mechanics of nonlinear sand response, including stiffness degradation, hysteretic damping, excess pore-pressure generation, cyclic mobility, and post-liquefaction deformation. It then synthesizes how PM4Sand has been implemented, calibrated, validated, and used in recent earthquake-geotechnical applications. A practical workflow is proposed for model selection, calibration evidence, response metrics, and engineering interpretation. The review further consolidates reported response trends with respect to seismic intensity, density state, and confinement, and critically discusses the benefits and limitations of PM4Sand in site response, liquefaction assessment, and soil-structure interaction problems. The main novelty of the paper lies in integrating constitutive theory, calibration logic, and engineering interpretation into a single analytical framework that can support future simulation-based studies and practice-oriented applications. This study is positioned as an analytical and workflow-oriented contribution, aiming to synthesize existing evidence and provide a structured framework for future simulation-based research.