2. Theoretical Model
2.1. Adsorption-Induced Swelling Strain
2.2. Adsorption-Induced Stress under Uniaxial Conditions
2.3. Mechanical Strength Change after Gas Adsorption
3.1. Swelling Strain and Swelling Stress
3.2. Stress and Strength Reduction
- There are a large number of coal mines that will be closed and some of them are located in deep formations in China. CO2 storage in abandoned coal mines could be a potential option for greenhouse gas disposal.
- The volume strain and swelling stress, as a function of time, and different loading pressure steps are deduced. Equation (15) is used to describe swelling stress considering coal has already had prior swelling deformation under the condition of step-by-step non-linear loading and a non-Langmuir isothermal model. The model presented in this paper is different from other models, in which only the initial state and the final equilibrium state are considered, and the incremental swelling process is neglected.
- A theoretical model based on linear swelling stress–strain work is proposed to calculate the reduction ratio of coal pillar strength under uniaxial conditions. This theoretical model can be used to describe strength reduction during adsorption under adsorption pressure loading step-by-step.
Conflicts of Interest
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