The characteristics of coal desorption strain play a crucial role in coal permeability, coalbed methane (CBM) recovery, and the prevention of outbursts. This study developed an improved thermomechanical diffusion–seepage (TMDS) coupling model to investigate the strain evolution during the gas desorption process in coal. The model considers the time-varying diffusion coefficient, the Klinkenberg permeability effect, and the impact of moisture on adsorption, amending the traditional coal deformation equation and coal permeability model. Utilizing this model, the study explored the mechanism, contribution, and spatiotemporal evolution of desorption strain, while analyzing quantitatively the effects of gas types and TMDS parameters on the dynamics of desorption strain. The results demonstrate that desorption strain consists of fracture pressure, matrix pressure, desorption action, and temperature effects, with desorption action being the predominant factor. The impact of gas type, especially CO₂, on desorption strain is significant, with CO₂ enhancing CH₄ desorption strain more than N₂. Additionally, the study explored the sensitivity of desorption strain to TMDS parameters, revealing that gas pressure, permeability, and Langmuir pressure significantly impact desorption strain. Desorption strain can serve as an indicator for predicting and evaluating the risk of outbursts, and the injection of low-temperature liquid nitrogen could help reduce this risk. This research provides insights for further understanding the desorption mechanism in gas-bearing coal, improving CBM recovery, and preventing disasters.

煤体解吸应变特征对于煤体渗透性、煤层气采收率和防治突出具有重要作用。本研究开发了一种改进的热机械扩散渗流（TMDS）耦合模型来研究煤中瓦斯解吸过程中的应变演化。该模型考虑了时变扩散系数、Klinkenberg渗透率效应以及水分对吸附的影响，修正了传统的煤变形方程和煤渗透率模型。利用该模型，研究探讨了解吸应变的机理、贡献和时空演化，同时定量分析了气体类型和TMDS参数对解吸应变动力学的影响。结果表明，解吸应变由破裂压力、基质压力、解吸作用和温度效应组成，其中解吸作用是主导因素。气体类型，尤其是CO ₂ ，​​对解吸应变的影响显着，其中CO _{2比N 2}更能增强CH ₄解吸应变。此外，该研究还探讨了解吸应变对 TMDS 参数的敏感性，揭示了气压、渗透率和 Langmuir 压力显着影响解吸应变。解吸应变可以作为预测和评估爆发风险的指标，而注入低温液氮有助于降低这种风险。该研究为进一步了解含瓦斯煤的解吸机制、提高煤层气采收率和预防灾害提供了见解。