The effective stress law and the permeability play a notable role in dealing with the gas-solid coupling problem of porous media. The key parameter to quantify the influence of pore pressure to effective stress is the effective stress coefficient α_ij. However, current relevant researches are mainly focused on the pore elastic flow characteristics in the elastic stage or hydrostatic pressure under conventional triaxial stress state, which are difficult to reflect the actual formation stress condition. To this end, the present study was conducted to investigate the influence of induced damage on the effective stress coefficient and the permeability of sandstone under true triaxial stress. The results showed that the effective stress coefficient and the permeability were closely related to the damage evolution and fracture propagation. α_ij exhibited obvious anisotropy, α₁ was larger than α₂ and α₃, and α₃ > α₂ appeared in the horizontal direction. α_ij increased with increasing the fracture density and opening, even greater than unity. Increasing the initial horizontal stress could reduce α_ij under the damage state. The elastic modulus E_ij also exerted anisotropy during loading, E₁ basically exhibited an increasing trend followed by a decrease as the axial strain increased, E₂ and E₃ were continue to degrade with increasing the axial strain. Loading the deviatoric stress could cause damage, which induced the initiation and propagation of microcracks, and in turn led to the nonlinear stress-strain relationship and volume expansion of the rock, so the permeability increased, and it had increased sharply before reaching the peak strength. Under the influence of σ₂, α_ij first increased and then decreased with increasing the intermediate principal stress coefficient b under the damage stage. The porosity effect also affected the relationship between α_ij and the permeability related to the induced damage, and α_ij revealed an increasing trend as the permeability increased.

有效应力定律和渗透率在处理多孔介质的气固耦合问题中发挥了重要作用。量化孔隙压力对有效应力影响的关键参数是有效应力系数α _ij 。但目前相关研究主要集中在弹性阶段或常规三轴应力状态下的静水压力下的孔隙弹性流动特性，难以反映实际地层应力状态。为此，本研究旨在研究诱发损伤对砂岩有效应力系数和渗透率的影响。在真正的三轴应力下。结果表明，有效应力系数和渗透率与损伤演化和裂缝扩展密切相关。α_ij表现出明显的各向异性，α₁大于α₂和α₃，水平方向出现α₃ > α₂α_ij随着裂缝密度和开度的增加而增加，甚至大于一。增加初始水平应力可以降低损伤状态下的α_ij弹性模量E_ij在加载过程中也表现出各向异性，随着轴向应变的增加， E ₁基本上呈现先增加后减小的趋势，E ₂和E ₃随着轴向应变的增加继续退化。加载偏应力会造成损伤，诱发微裂纹的萌生和扩展，进而导致岩石的非线性应力-应变关系和体积膨胀，使渗透率增加，在达到峰值强度前急剧增加. 在σ ₂的影响下，α _ij随着中间主应力系数b的增大先增大后减小在损坏阶段。孔隙度效应也影响了α _ij与诱发损伤相关的渗透率之间的关系，并且α _ij随着渗透率的增加呈增加趋势。