A Modeling Method for Sediment Multi-field Coupling Model Considering Hydrate Dissociation

Abstract

The invention belongs to the technical field of geotechnical engineering, and provides a modeling method of a sediment multi-field coupling model taking hydrate decomposition into account. According to the modeling method, on the basis of a pore-medium mechanical basic theory, in combination with the mechanical characteristics, flow characteristics and heat-transfer characteristics of hydrate sediment, control equations and constitutive equations of physical and mechanical behaviors of the hydrate sediment are given. By the adoption of a PDE module in COMSOLM ultiphysics software, the control equation discretization of temperature, pressure and saturation degrees is achieved, an outer material interface in a structural mechanical module is adopted, and a hydrate-sediment critical-state constitutive model based on a thermodynamics method is embedded. Meanwhile, a return mapping algorithm of a backward euler integral format is adopted, C++ language is adopted to write a model program, and numerical simulation and analysis, taking the hydrate decomposition process into account, of the physical and mechanical behaviors of the sediment are achieved.

Description

technical field [0001] The invention belongs to the field of geotechnical engineering, and in particular relates to a modeling method of a sediment multi-field coupling model considering hydrate decomposition. Background technique [0002] Natural gas hydrate has huge global reserves and is widely distributed. As a potential alternative energy source, it has attracted great attention from governments all over the world. However, natural gas hydrates mostly occur in permafrost areas and continental margins, and are difficult to mine. The mining process will cause deformation of sedimentary layers. Unreasonable mining will lead to stratum subsidence and submarine landslides, and may induce tsunamis, greenhouse effects, etc. disaster. Therefore, it is particularly important to study the physical and mechanical properties of gas hydrate deposits. However, the hydrate dissociation process is complex and involves multi-field coupling of phase transitions contained in multiphase ...

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Problems solved by technology

In China, Wu Erlin et al., Cheng Yuanfang et al. proposed corresponding multi-field coupling models for the engineering problems caused by hydrate decompression and decomposition, but the models all use relatively simple constitutive relations, which cannot describe complex mechanical behaviors.

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