## 3 Highlights and Key Contributions of Published Articles
### Mining Engineering  
Due to the long-standing and strong demand for mineral resources driven by human activities, the complex issues encountered in mining engineering have become a key focus for researchers. Mining-induced seismicity refers to seismic events caused by changes in the stability of rock masses resulting from mining activities. [PERSON] et al. (contribution 8) evaluated mine seismicity and its associated risks in the Ordos mining area of North China, where thick hard-bedded sandstone formations overlay Jurassic coal seams. Frequent seismic events in this region have disrupted production and threatened the safety of large-scale mining operations. Their research explores the mechanisms behind these seismic events, particularly in goat working faces with multi-layer thick hard roofs, and proposes prevention strategies. They find that an \"advanced and lateral\" L-form roof structure contributes to seismic activity, exacerbated by factors such as the breaking of the multi-layer roof, bending and prying effects, and uneven mining speeds, especially when the exceedance warning index is breached. To mitigate these events, the study suggests coordinated blasting along roadways and within the working face, which has proven effective in field applications. These findings provide valuable insights into developing seismic control technologies, supporting resource development and energy security in deep mines. [PERSON] et al. (contribution 22) explored the impact of mining speed on the overlying strata's deformation and energy release through theoretical analysis, numerical simulation, and the digital speckle method. The temporal and spatial evolution characteristics of the impact energy during mining were simulated. This observation corroborates that escalating mining speed augments the energy dispensed by the breaking of the upper rock. Consequently, this escalation induces a transformation in the energy levels of mine earthquakes, culminating in a heightened incidence of large-energy mine earthquakes. Hydraulic fracturing is a widely used technology in mining engineering and oil and gas extraction. Its main principle involves injecting high-pressure fluids into underground rock layers to create fractures, thereby increasing the recovery rate of mineral resources. Improvements to this technology, as well as its potential environmental impacts and sustainability issues, are hot topics of research. In an extraordinarily thick and hard roof, [PERSON] et al. (contribution 4) studied the dynamic disaster mechanism induced by the hydraulic fracturing of vertical wells on the ground through field investigation, accident case analysis, a similar-material simulation test, and theoretical analysis. The hydraulic fracturing technologies of cross-arranged vertical-surface deep and shallow wells and the hydraulic fracturing technology of cross-perforated surface multi-branch horizontal wells are proposed for an extremely thick hard roof to avoid the dynamic disaster of overall sliding movement induced by surface hydraulic fracturing. [PERSON] et al. (contribution 20) investigated using hydraulic fracturing to address safety issues caused by hard roofs in underground coal mines. Numerical simulations and field tests were conducted to determine the optimal fracturing parameters. The results showed that hydraulic fracturing effectively reduced roof pressure, destroyed cantilever beam structures, and decreased stress concentration, enhancing mining safety. This work offers theoretical and technical support for managing hard roofs in mining operations. [PERSON] et al. (contribution 21) investigated directional hydraulic fracturing (DHF) in coal mining, focusing on the re-orientation of hydraulic fractures (HF). Experiments with gelatin samples revealed that HF re-orientation is influenced by the ratio of differential stress to elastic modulus, not their absolute values. Fractures can propagate asymmetrically and form step-like geometries. This research offers insights and recommendations for effective DHF application in coal mines.