Due to active actions of groundwater and geothermal, the stability of underground engineering is important during geological structure active area. The damage mechanical theory and statistical mesoscopic strength theory based on Weibull distribution are widely used to discuss constitutive behaviors of rocks. In these theories, a statistical method is used to capture mesoscopic properties of rocks in order to generate a realistic behavior at a macroscopic scale. Based on the above theories, this paper aims at establishing a constitutive relation of brittle rocks under thermal-mechanical coupling conditions. First, a statistical damage constitutive model was established by considering the thermal effects and crack initiation strength. Subsequently, the parameters of the model were determined and expressed according to the characteristics of stress-strain curve. Third, the model was verified by conventional triaxial experiments under thermal-mechanical actions, and the experimental data and theoretical results were compared and analyzed in the case study. Finally, the physical meaning of the parameters and their effects on the model performance were discussed.

Using the techniques of X‐ray diffraction, polarizing microscopy, uniaxial compression, and scanning electron microscopy (SEM), the relationships between the microfracture features and mineral morphology of granite were studied. The results showed that feldspar, quartz, and biotite are the main components of the granite samples in this study. Biotite has a self‐shaped flake structure with perfect cleavage. K‐feldspar has a lattice double crystal structure with two groups of cleavage. Plagioclase has a semi‐self‐shaped plate structure with two groups of cleavage. Quartz is prismatic or granular and exhibits noncleavage. The microfracture features of biotite are flaky with exfoliation, and flake cleavage fracture is mainly determined by its peculiar flaky cleavage. Feldspar (K‐feldspar and plagioclase) is plate, layered, or two groups of cleavage and is also mainly determined by its peculiar two groups of cleavage. The microfracture features of quartz are highly irregular, with many randomly distributed intergranular and transgranular cracks, small particles or granule bulges, similar to quartz crystal, and this is due to the noncleavage feature of quartz itself. It is demonstrated that microfractures are preferentially ruptured along cleavage planes for these granite minerals under the action of external forces.

The three-parameter Weibull distribution has a strong ability to fit many kinds of experimental data, which provides a solution for using a unified expression to characterize the elastic-brittle, strain softening, elastic-plasticity, and other constitutive behaviors of rocks. Therefore, a statistical damage constitutive model based on three-parameter Weibull distribution was constructed through theoretical analysis and derivation. Its expression ability was verified by combining with the conventional triaxial compression test data of marble. Meanwhile, the application effect of this statistical damage constitutive model on granite and sandstone was analyzed. The results show that the statistical damage constitutive model of rock based on three-parameter Weibull distribution can well express elastic-brittle, elastic-plastic, strain softening behaviors of rock by setting reasonable constitutive parameters, which lays a theoretical foundation for constructing a unified rock constitutive model. Conventional triaxial tests of marble show that with the increasing of confining pressure (⁠ $σ3$= 5, 15, 25, 35 MPa), the plastic deformation increases and the failure mode gradually changes from brittle tensile failure to shear failure, showing brittle-ductile and brittle-plastic transition characteristics. And its constitutive behaviors are characterized by elastic-brittleness, strain softening, and elastic-plasticity, which can be well expressed by the statistical damage constitutive model. When $σ3$ is 25 and 35 MPa, sandstone samples show elastic-brittle behavior. And for granite samples, they show strain softening behavior when $σ3$ is 5 MPa. The statistical damage constitutive model is also suitable for describing both sandstone elastic-brittle behavior and granite strain softening behavior. It is concluded that the three-parameter Weibull distribution provides a useful approach to characterize various constitutive behaviors of rock, and the model has a wide potential in numerical simulation for mining engineering, geoengineering, and other rock engineering.

Slope deformation and failure is an inevitable engineering problem in highway construction and operation in mountainous areas. Its essence is a continuous–discontinuous gradual failure process of slope under the action of unbalanced force. Slope deformation and failure mechanism is the basis and key content of its emergency treatment and comprehensive treatment. In this study, the continuous–discontinuous element method (CDEM) and finite difference method are used to analyze the deformation mechanism and support the effect of a scattered slope in the Biwei Expressway. The results showed that the change in the local geological environment caused by roadbed excavation leads to slope slippage along the surface and then pulls the upper rock mass gradually to produce slippage failure, resulting in the stability gradually decreasing. The mechanism is traction sliding–tensile cracking. The continuous–discontinuous element method can effectively simulate the formation process of the main and sub sliding planes during excavation and can better display the phenomenon of slope failure and gradual disintegration. The emergency disposal of the gravity anti-sliding retaining wall in front of the slope can effectively control further deformation and ensure temporary stability. In comprehensive treatment, step-type slope excavation, gravity anti-sliding retaining wall, and anchor frame beam are adopted to control the deformation and failure of slope and ensure long-term stability. The numerical simulation results are consistent with the actual results, which effectively explains the rationality of this study. The research results of this study can provide some reference for the emergency treatment and comprehensive treatment of slopes in mountainous areas and for the construction and operation of highways and other infrastructure in mountainous areas.

The mountainous areas in the western part of Sichuan Province are mostly Alpine Gorge regions with high mountains, steep slopes, complex topography and geomorphology, special climatic conditions, infertile soils, and fragile ecological environments. In this study, a geohazard risk assessment was carried out in the Alpine Gorge region to prevent geohazards from hindering socio-economic development, affecting the lives and safety of residents, and undermining sustainable development in the region. With the help of a geographic information system (GIS), the analysis of geohazard influence factors was carried out; eight indicators, such as elevation and slope aspect, were selected to construct the evaluation index system. Additionally, the time and space distribution pattern of each influence factor and geohazard was analyzed. Geologic hazards in the region are influenced mainly by precipitation and human engineering activities. The prediction and evaluation of geohazard risk in Jiulong County are based on the Information Value model (IV), the Logistic Regression model (LR), and the Random Forest model (RF). Comparing the Receiver operating characteristic (ROC) curves of the three models for the accuracy test, the results show that all three models are suitable for the Alpine Gorge region, and the Logistic Regression model has the highest accuracy. Based on the evaluation results, measures and countermeasures for geologic disaster prevention and mitigation are proposed in light of the reality of geologic disaster prevention and mitigation work in Jiulong County. The research results can guide the government’s disaster prevention and mitigation work, provide a scientific basis for formulating regional geologic disaster prevention and control strategies, and ultimately promote the region’s sustainable development.