A thermo-hydro-mechanical-biochemical coupled model for landfilled municipal solid waste

The rapid development of urbanization in China has generated large amounts of municipal solid waste (MSW), which can contribute to certain dangers in landfills, such as liner ruptures, heap landslides, and landfill gas explosions. Therefore, a comprehensive and coupled model is necessary for landfill design and verification. In this study, a thermo-hydro-mechanical-biochemical (THMBC) coupled model is proposed, which considers biological degradation, skeleton deformation, particle compressibility, intra-particle water release, two-phase flow, pore water evaporation and condensation, and heat and solute transport. In the model, biochemical reaction rates are utilized to link the fluid source terms with the solid-mass loss, and to link the heat transport with biochemical reactions and other processes. Two cases were studied and utilized to verify the applicability of the proposed model in homeothermic and high-temperature (40 ?C) circumstances via OpenGeoSys software and the ZJU Calculator, and the results of both case studies were found to agree with the measured experimental data. In general, this work provides a basic framework for the simulation of THMBC coupling in landfills. In future research, this framework can be improved by implementing more alternative constitutive equations in a single process.