Understanding the permeability properties and mechanical behavior of rock under coupled hydromechanical loading is crucial for deep-underground engineering applications. In this study, a set of triaxial compression-permeability tests under various confining pressures ( \(p_{c}\) ) and pore pressures ( \(p_{w}\) ) were carried out to understand the mechanical properties and permeability evolution of argillaceous sandstone. The experimental results show that the deformation and permeability evolution can be divided into different stages by stress thresholds, including crack-closure stress, crack-initiation stress, and peak strength. With the increase of \(p_{c}\) , the stress thresholds increase, and the rock permeability decreases, whereas \(p_{w}\) exhibits the opposite influence. The strain sensitivity of permeability when \(p_{c} = 10{\text{ MPa}}\) is greater than that when \(p_{c} = 30{\text{ MPa}}\) , which can be attributed to the initial rock compaction. The permeability first declines exponentially with the increase of the external load before it recovers. Compared to the permeability recovery when \(p_{c} = 10{\text{ MPa}}\) , the permeability recovery when \(p_{c} = 30{\text{ MPa}}\) is much less obvious, which may be attributed to the pore collapse within the rock under high confining pressure. We proposed a damage-based permeability model to fit the experimental results. This model considers the interaction of the matrix, fractures within the matrix, and fractures between the matrix. This study shed light on the rock permeability evolution under coupled hydromechanical loading.
