The deterioration of rock mass in the Three Gorges reservoir area results from the coupled damage effects of macro-micro cracks and dry-wet cycles, and the coupled damage progression can be characterized by energy release rate. In this study, a series of dry-wet cycle uniaxial compression tests was conducted on fractured sandstone, and a method was developed for calculating macro-micro damage (DR) and energy release rates (YR) of fractured sandstone subjected to dry-wet cycles by considering energy release rate, dry-wet damage and macro-micro damage. Therewith, the damage mechanisms and complex microcrack propagation patterns of rocks were investigated. Research indicates that sandstone degradation after a limited cycle count primarily exhibits exsolution of internal fillers, progressing to grain skeleton alteration and erosion with increased cycles. Compared with conventional methods, the DR and YR methodologies exhibit heightened sensitivity to microcrack closure during compaction and abrupt energy release at the point of failure. Based on DR and YR, the failure process of fractured sandstone can be classified into six stages: stress adjustment (I), microcracks equal closure (II), nonlinear slow closure (III), low-speed extension (IV), rapid extension (V), and macroscopic main fracture emergence (VI). The abrupt change in damage energy release rate during stage V may serve as a reliable precursor for inducing failure. The stage-based classification may enhance traditional methods by tracking damage progression and accurately identifying rock failure precursors. The findings are expected to provide a scientific basis for understanding damage mechanisms and enabling early warning of reservoir-bank slope failure. (c) 2025 Institute of Rock and Soil Mechanics, Chinese Academy of Sciences. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/ 4.0/).

The salinization of sulfate saline soil in frozen regions can lead to severe potential environmental hazards, such as increased salt heaving and collapsibility. Corn stalk ash (CSA), a typical agricultural waste that is non-polluting to soil, groundwater, and the environment, possesses high pozzolanic activity and is a potential amendment for sulfate saline soil. To verify the feasibility of using CSA to improve sulfate saline soil, a series of experiments were conducted to study the effects of CSA content, salt content, and freeze-thaw cycles on the mechanical properties of the improved soils. A statistical damage constitutive model was established that comprehensively considers the coupled effects of freeze-thaw, salinity, moisture, and loading to more accurately describe the improvement effects of CSA. The study shows that CSA is highly effective in improving sulfate saline soil. The application of this method can significantly increase the unconfined compressive strength (UCS) of sulfate saline soil and greatly enhance their freeze-thaw resistance. The best improvement effect was observed with a CSA content of 15%. Furthermore, the coupled statistical damage constitutive model more accurately and intuitively analyzed the entire deformation and failure process of the improved soil under coupled effects, showing that the addition of CSA enhances the brittle characteristics of the improved soil while reducing its plastic deformation and ductile failure characteristics. In summary, the method of using CSA to improve sulfate saline soil is highly effective and environmentally friendly, providing a theoretical basis for improving sulfate saline soil in seasonally frozen regions.

A statistical damage model is proposed to investigate the impacts of the interface roughness and the shear area of the soil on shear deformation characteristics at the soil- structure interface. Assuming that the damage to the soil shear plane and the soil-structure interface follows Weibull distribution damage theory, the model introduces an equivalent initial damage factor that considers the effect of interface roughness. Results indicate that the interface roughness and soil shear area considerably influence the shear stress-displacement relation at the soil-structure interface. Under the same normal stress, the strengths of the soil-structure interface and the soil shear plane approach with increasing interface roughness and soil shear area. Furthermore, the total damage to the soil shear plane during sample loading is due to load-induced damage, whereas the total damage to the soil-structure interface comprises the equivalent initial damage, load-induced damage, and coupled damage arising from the interactions between the equivalent initial damage and load-induced damage. The feasibility of the model was verified by comparing the theoretical and experimental results, which indicate that the model can well predict the shear deformation behavior of the soil-structure interface under different soil shear areas and interface roughnesses.