Empirically Based Constitutive Modeling Approach for Methane Hydrate‐Bearing Soils

Abstract Over recent years, substantial efforts have been devoted to developing reliable geomechanical models for methane hydrate‐bearing sediments (MHBS). Understanding MHBS behavior is critical for simulating engineering processes related to methane extraction from hydrate‐rich deposits worldwide. Methane hydrate, a solid ice‐like substance forming within soil pores, significantly changes the sediment behavior. Numerous constitutive models have been proposed, mostly adapted from frameworks originally designed for conventional soils. Notably, different models, often based on contrasting assumptions, can reproduce the same experimental data—highlighting the complexity of capturing the true mechanical trends of MHBS. This paper presents a new approach in which essential mechanical features, including yield criterion, flow rule, and strain‐hardening behavior, are derived directly from experimental observations, independent of prior modeling assumptions. By mapping experimental data into a continuous stress space, the essential behavioral trends and their shape functions are directly identified. The results reveal clear key features: deviatoric hardening, an almost flat yield surface, and a non‐associative flow rule. These characteristics are integrated into a new constitutive model tailored for MHBS, offering a more direct and empirical basis for understanding and predicting their mechanical response in engineering applications.