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Coal rock dynamic disasters such as rockburst and gas outbursts pose severe threats to the safe and efficient mining of coal mines in China; however, the mechanical mechanisms of those disasters are still unknown. Therefore, the evolution law and constitutive model of damage and fracture of coal rock was emphatically studied, starting from the rockburst-gas disaster that occurred at the coal mine roadway. Firstly, the X-ray high-precision micro-CT scanning experiment was performed, and the high-resolution 3D digital core of burst-prone coal was built utilizing 3D reconstruction technology. Furthermore, the box-counting dimension method and the 3D visual image processing software AVIZO were used to calculate the characteristic parameters of mineral bands and crack structures inside the coal sample. Secondly, a damage-fracture constitutive model considering three-parameter Weibull distribution, gas influence, and effective stress was proposed, based on CT scanning reconstruction and statistical strength theory. Thirdly, the triaxial compression experiments of gas-bearing coal were conducted, the model parameters were calculated using experimental results, the model was verified, and the damage evolution law of the progressive failure process of coal rock was revealed. Specifically, the experimental results of micro-CT scanning reconstruction and fractal calculation show that the surface area ratio and fractal dimension of the mineral bands are 0.0035−0.0137 and 1.1214−1.2342 respectively, while that of the fracture structures are 0.0006−0.0040 and 1.0651−1.1454 respectively. The surface area ratio and fractal dimension of mineral bands are generally larger than those of fracture structures, indicating that the number of discontinuous structures of burst-prone coal is significant, and its distribution is complex. Furthermore, the experimental results show that stress-strain curves are characterized by the class I curve; shear fracture usually occurs under triaxial compressive loads. The peak strength and peak strain increase with the rise in confining pressure. Moreover, the determination method of seven parameters within the damage fracture model is given, and those parameters and damage variable are solved based on experimental results. The calculation results show that this model can accurately reflect the progressive failure characteristics of coal rock, such as compressive deformation, quasi-linear elastic deformation, plastic deformation, peak strength, and post-peak softening. Additionally, in the first two stages, the damage variable of coal rock is less than 0.2. When it enters the plastic stage, especially in the post-peak step, the damage variable increases sharply until the failure occurs. Hence, the concept of damage threshold is proposed; here, the damage threshold of 0.2 is recommended as the early warning value of damage fracture of coal rock. The findings will further promote the development of damage mechanics and provide a theoretical basis for the prevention and control of coal and rock dynamic disasters.

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[Objective] Exploring the driving factors and dynamic change characteristics of the coupling relationship between ecosystem service trade-offs and synergies is crucial for clarifying the mutual feedback mechanism of social-ecological systems in the context of ecological restoration. [Methods] In this study, we selected Yan’an City, a typical vegetation restoration area, as the study area, and quantified four ecosystem services including carbon sequestration, water yield, baseflow regulation, and soil conservation from 2000 to 2020. Then we used a comprehensive ecosystem services index (ESI) to characterize the coupling relationship between the four ecosystem services. Based on the Bayesian belief networks (BBNs) model, we developed a network structure, which captured the driving factors of ESI and identified the variation characteristics of ESI. [Results] The results show that: (1) The ESI of Yan’an City increased significantly from 2000 to 2020, with the high value areas of ESI expanded from the middle to the north and south of the city, and the low value areas of ESI concentrated around the town and the northern fringe area. The baseflow regulation steadily declined since 2000. (2) The combined contribution rates of precipitation, fractional vegetation cover (FVC), actual evapotranspiration, and temperature to the change of ESI were more than 70% in 2000 to 2020, in which precipitation and FVC were the dominant driving factors. (3) In the 20-year study period, the contribution rate of precipitation showed a fluctuating downward trend but the contribution rate of FVC kept rising. According to the scenarios of probabilistic inference of BBNs, increasing temperature and precipitation will aggravate the risk of loss for baseflow regulation, while the continuous vegetation restoration will also lead to the threshold effects for the optimization of ESI. [Conclusion] A long-term monitoring of vegetation restoration areas and the improvement of baseflow regulation should be the priorities for Yan’an City in order to maintain the effectiveness of vegetation restoration and to cope with climate change and human disturbances in the future.