Coalbed methane (CBM) reservoirs show unique stress responses due to the additional sorption-induced effect under subsurface in situ condition. An insight of dynamic stress evolution is important to CBM development and carbon sequestration in coals. In this study, the combined controls of geomechanical effect and sorption-induced effect were gained to determine in situ stress evolution and predict mechanical failure in coals under uniaxial strain condition for various gases. We conduct a series of experimental measurements on stress path responses with continuous gas depletion for helium, N₂, CH₄ and CO₂. The proposed model is validated by the experimental data, and then, we theoretically analyzed the stress evolution and potential mechanical failure behaviors for CBM operations. The applied horizontal stress was found to continuously decrease for all gas types with pressure depletion under uniaxial strain condition. Sorbing gas showed a higher excessive stress loss with the same decrement of gas pressure than that in non-sorbing gas depletion which is attributed to the sorption-induced effect. For helium depletion, horizontal stress variation is mainly controlled by geomechanical effect. Theoretically, coals with high gas affinity can induce relatively large horizontal stress loss. This excessive stress loss can trigger the localized instability of coal mass due to deviatoric stress trigger shear failure.

煤层气（CBM）储层表现出独特的应力响应，这是由于地下原位条件下的附加吸附诱导作用所致。动态应力演化的洞察力对煤层气的发展和碳固存具有重要意义。在这项研究中，获得了岩土力学效应和吸附诱导效应的组合控制，以确定原位应力演化并预测了在各种气体的单轴应变条件下煤的机械破坏。我们对氦，N ₂，CH ₄和CO ₂连续消耗气体的应力路径响应进行了一系列实验测量。实验数据验证了所提模型的有效性，然后从理论上分析了煤层气作业的应力演化和潜在的机械破坏行为。发现在单轴应变条件下，随着压力的降低，所有气体类型所施加的水平应力会持续降低。与不吸收气体的消耗相比，在相同的气体压力下降下，吸附气体表现出更高的过度应力损失，这归因于吸收引起的效应。对于氦的消耗，水平应力的变化主要由地质力学效应控制。从理论上讲，具有高瓦斯亲和力的煤会引起相对较大的水平应力损失。由于偏应力触发剪切破坏，这种过度的应力损失会触发煤团的局部失稳。