The desert bottomland of Northern Shaanxi, China, features an ecologically fragile environment with a pronounced mismatch between abundant coal resources and scarce water resources. Large-scale coal mining often impairs the water-resisting capacity of overlying strata, leading to shallow groundwater depletion, surface drought, and vegetation degradation. This study focuses on determining the height of the water-conducting fractured zone (WCFZ) and assessing shallow groundwater loss in such ecologically sensitive mining areas. Through analysis of measured WCFZ heights, the empirical formulas currently specified in national codes are found to be inapplicable to the study area. A multi-factor nonlinear prediction model, better suited to local conditions, is therefore established using multiple nonlinear regressions. Taking the Jinjitan Coal Mine as a case study, a 3D hydrogeological conceptual model is developed using FEFLOW to simulate phreatic water responses to mining activities. The results indicate a maximum phreatic water drawdown of 3-4 m, with post-mining burial depths predominantly ranging from 5 to 8 m, reaching a warning level that requires attention and mitigation. This study provides a valuable reference for water hazard prevention and ecological protection in desert bottomland regions.

Mining of coal seams with a large mining height will cause a water-conducting fractured zone (WCFZ) to develop, which can cause a mine water disaster when it connects to a roof aquifer. The coal seam in the northern part of the Laohutai Coal Mine is characterised by its considerable depth and substantial mining height. A numerical model of the super-thick coal seam layered mining was established and FLAC3D was used to simulate the development of the WCFZ. The results indicated that although layered mining would also cause a WCFZ to develop, the development rate of the WCFZ would decline after several layers were mined, and the ratio of the height of the WCFZ (HWCFZ) to the mining thickness would decrease from 15.78 to 4.89. The top of the WCFZ was determined by loss of drilling fluid measured in situ and this measurement was comparable to the simulation outcomes. Consequently, an empirical formula was developed to predict the HWCFZ; the result conformed to the variation trend of the power function. Furthermore, borehole TV logging revealed fractures of the borehole wall, which showed that the top of WCFZ had a burial depth of 175.50 m. Finally, mining area were demarcated within the mine’s 73,010 working face where mining thicknesses were limited to heights of 4 and 9 m.

The flow behavior of heterogeneous ice–rock particle systems on inclined surfaces is crucial for understanding ice–rock debris flows in cold regions. In this research, the discrete element method (DEM) was used to investigate the kinematic and micromechanical characteristics of ice–rock particle systems under different ice contents and slope angles. Key parameters, including velocity, kinetic energy, coordination number, stress distribution, centroid separation, and inertial number, were analyzed to clarify the combined effects of particle composition and slope inclination. The results show that kinetic energy first increases and then decreases during flow evolution. Pure ice and pure rock systems exhibit higher flow velocities than mixed systems, indicating reduced mobility in heterogeneous mixtures. Higher ice content shortens the time required for ice–rock separation, while steeper slopes further accelerate this process. When the ice-to-rock volume ratio approaches unity, the coordination number reaches a minimum. Moreover, unlike the nearly uniform inertial number distribution observed in pure granular systems, ice–rock particle systems display higher inertial numbers in the upper region and lower values near the base.

This study identifies and characterizes a distinct short-period bed-separation water inrush (SP-BSWI) hazard in the Ordos Basin, an accelerated form of the conventional hazard where separated roof strata accumulate water that floods underground workings. A SP-BSWI exhibits dramatically shorter recurrence cycles (11 vs. 94 days) and spatial intervals (52 vs. 255 m). This abnormal recurrence is mechanistically driven by the self-sealing properties of the regional K₁/J₂ paleoweathered crust (PWC), which is rich in clay minerals and highly expansive, enabling rapid fracture healing and establishing a cyclical inrush→sealing→recharge→re-inrush disaster pattern. Based on this mechanism, we developed a quantitative model to predict PWC self-healing from geophysical logs and integrate it as a dynamic core into a novel variable weight model (VWM) for SP-BSWI risk evaluation. Field validation demonstrates that the VWM predicts actual inrush locations with 83.3

The mechanism of mud-sand inrush during coal mining under paleoweathered rock (PWR) in the K1/J2 contact zone of the Ordos Basin is unclear, which seriously restricts the safety production of mines. Based on this, a physical model device of mud-sand inrush with adjustable crack width was developed, and the start-up and transport evolution experiments of PWR particles with different clay mineral contents (i.e., 21.03

Underground space excavation, particularly in mining operations, significantly compromises the integrity of overlying rock-soil structures and ground infrastructure, resulting in issues. This study discusses how different overburden combination structures affect the development of mining-induced fractures and further predicts the height of the fractures in weakly consolidated formations in Western China. Using the matrix discrete element method, we analyzed the evolution and height development of water-conducting fractured zones (WCFZs) under three composite structures, including upper soft-lower hard (USLH), upper hard-lower soft (UHLS), and soft-hard interbedded (SHI) strata. Besides, field-measured data collected from weakly consolidated strata in Western China are applied to develop an empirical formula for predicting the failure height of the weakly cemented formations. The research results show that: (1) the mining-induced fractures develop more rapidly in hard rock than soft rock, and the steady fracture height varies significantly across different composite structures. (2) Based on the analysis of vertical stress, break heat distribution, and element connection, the mining-induced fracture height is highest in the UHLS strata ( 130 m), followed by the SHI strata ( 105 m) and then the USLH strata ( 91 m), respectively. (3) The proposed formula, validated by measured data, demonstrates high prediction accuracy (94.89

Water inrush poses a serious threat to the safety and sustainability of coal mining operations, particularly in arid-semiarid regions where confined aquifers overlie coal seams. Therefore, an accurate assessment of roof water inrush risk is essential to prevent water hazards on the roof. In this study, a water abundance assessment model was developed for the Zhuanlongwan mining area (ZMA) to identify zones of varying inrush vulnerability. In the model, five key controlling indicators, that is, the roof-sandstone thickness, fault density, unit inflow, hydraulic conductivity, and lithologic coefficient, were determined with the fuzzy analytic hierarchy process (FAHP) and Random Forest (RF) approaches, and the roof aquifer was subsequently classified by using the natural breaks classification method (Jenks). The model performance was validated through metrics of the overall accuracy (A), Cohen ' s kappa coefficient, and the area under the receiver operating characteristic curve (AUC). Furthermore, the water inrush effect is also affected by the roof geological properties. By considering the relation between roof water abundance and the residual roof layer thickness influenced by the water-conducting fracture zone (WCFZ), a synthetic water inrush risk assessment system was finally organized, classified into four categories: the water-inrush risk zone, potential leakage zone, relative safe zone, and the safe zone. The results demonstrated a high level of agreement between predicted and observed vulnerability patterns, indicating the robustness of the FAHP-RF approach. This study provides a practical and data-driven framework for evaluating the water abundance of roof aquifers and mitigating water inrush hazards in arid-semiarid confined coal seam mining.

Fault activation is a common phenomenon during coal seam mining in proximity to faults. To better understand the mechanism of roof water hazards caused by fault activation, numerical simulation was employed. By coupling FLAC3D with PFC3D, this simulation is mainly analyzed from four aspects: the number of contact forces, the evolution of vertical displacement, the development of the plastic zone, and vertical stress. Based on field test and numerical simulation, this study reveals that fault activation becomes more intense as the working face advances from the hanging wall to the footwall of the fault. In addition, fault activation exhibits distinct phases, each characterized by different mechanical behaviors. Furthermore, combined with the decreasing trend in the number of contact forces, the height of the water-conducting fracture zone shows a pattern of initial increase followed by subsequent decrease. These findings reveal that analyzing the mechanism of roof water hazards caused by fault activation provides a theoretical basis and valuable insights for preventing and controlling roof water hazards during coal mining operations near faults.

Accidents and ecological environment deterioration associated with mining operations are prevalent, especially in Western China quarries, where special geological sedimentation forms the weakly cemented strata. The physical properties of the weakly cemented rocks are contrasted with those of the rocks from eastern China. Besides, this study investigates the mining-induced failure of the overburden through MatDEM software and field measurements. A fiber grating sensor online monitoring system was built to obtain the response feature of caving materials. The results indicate the mechanical strength of mudstone and siltstone is greater than that of sandstone, which is the reverse in eastern China. In addition, the natural porosity is greater than that of rocks in the eastern region. The development height of the mining-induced failure, including water-conducting fractured zone and caving zone, varies from 142.95 m to 152 m. The predicted value obtained through the empirical formula deviates greatly from the measured value. The range of the caving zone is indirectly calculated to be 47.80 m through the pressure sensor. The cyclic processes of crack compaction and formation lead to fluctuations in osmotic water pressure. Caving materials exhibit excellent water absorption and retention properties. Field water temperature measurement explains why the sensor temperature changes. This study provides valuable insights into the failure mechanisms of the weakly cemented overburden and the compaction behavior of caving materials.

Fault activation is a common phenomenon during coal seam mining in proximity to faults. Fault activation significantly exacerbates the risk of roof water hazards through multiple mechanisms. To better understand the mechanism of roof water hazards caused by fault activation, numerical simulation and physical experiments were employed. By coupling FLAC3D with PFC3D, it was demonstrated that fault activation occurs in a phased manner, essentially involving the processes of shear failure and fracture propagation. During coal mining, fault activation induces stress concentration at fault ends and a substantial increase in the height of the water-conducting fracture zone. Furthermore, the degree of fault activation positively correlates with the advance distance; more active faults exhibit greater maximum subsidence per unit advance distance. Physical experiments demonstrate that fault activation exhibits a negative correlation with the pore water pressure required based on fault dip angle and width. These findings reveal that considering the influence of Quaternary aquifer water pressure on fault activation provides a theoretical basis and valuable insights for preventing and controlling roof water hazards during coal mining operations near faults.

Coal-water resources are always necessities for industrial production and living needs. However, a sharp contradiction exists between coal exploitation and groundwater protection. One of the most important steps is to investigate the aquifer water yield property (WYP). In this study, the Dananhu No.7 coal mine is considered as a study case to analyze the WYP zonation of the middle Jurassic sandstone aquifer. The entropy weight method (EWM) and criteria importance through intercriteria correlation (CRITIC) are applied to determine the weights of evaluation indicators, separately. The combination weight matrix is obtained using the least square method (LSM). After that, we utilize the fuzzy comprehensive evaluation method (FCEM) to identify the zonation of aquifer water yield property. The WYP levels are divided into level I—level IV. The water inflow of the panels and the water release volume of the holes further verify the prediction accuracy. Besides, comparison methods, including CRITIC, EWM, and principal component analysis (PCA), are selected to illustrate the superiority of the nonlinear combination method. The results show most of the area is covered by the level II and III zones, while the level I and IV zones only appear near the southern and northeastern regions. The prediction performance of the nonlinear combination method is better than that of other methods after comparison. Finally, a management concept of coal-water dual resources is proposed through the safety and feasibility analysis. This study can serve as a scientific reference to realize eco-environment protection and safe mining for western China mining areas.

During the development of coal resources in China, mine bed-separation water damage has become a new type of disaster in recent years, bringing severe casualties and economic losses to mining areas. This study aims to solve the limitations of the existing bed-separation calculation methods. It proposes a new method of bed-separation discrimination based on the bending deflection of rock strata and a spatial volumetric calculation model that considers the development stage of bed separation. The improved stepwise comparison combination method (ISCCM) was combined with the theory of thin elastic plates to determine the developmental stage of the bed separation, which was able to predict the location of the bed separation and its volume more accurately. An example analysis of the 21301 working face in Cui mu Coal Mine, Shaanxi Province, shows that the proposed method exhibits higher accuracy and reliability in predicting the location of bed-separation development and the water inrush risk. The study shows that changes in the morphology of bed-separation development significantly affect the amount of water accumulation, and the traditional calculation method may produce a significant error after long-distance coal mining. This research result helps to improve the early warning ability and management effect of water damage in the mine bed separation. It provides technical support for the safe and efficient production of the mine.

With the gradual increase in coal production capacity, the problem of water damage from the coal seam roof is becoming more and more prominent. Neogene loose strata overlie coal seams in eastern China, and pressurized aquifers commonly lie at the bottom of the loose strata. The aquifers are mainly composed of unconsolidated sand, gravel, and weakly consolidated marl, which has strong permeability and an extremely unfavorable impact on safe production. Identifying the target area to prevent and control roof water damage can reduce the likelihood of water damage accidents in mines. This study takes the 85 mining district of Wobei mine as an engineering case. The discriminant indexes are selected for aquifer thickness, gradation coefficient, marlstone thickness, permeability, grouting quantity, and grouting termination pressure. A model integrating the newly proposed Crowned Porcupine Optimization (CPO, 2024), Convolutional Neural Network (CNN), and Bidirectional Long Short-Term Memory (BiLSTM) was constructed to predict unit water influx. A zonal map was generated based on the expected unit water influx of the fourth aquifer after grouting. In addition, the prediction results are compared with those from other models. Results indicate that the CPO-CNN-BiLSTM model achieves a higher accuracy and fewer errors in water abundance prediction, with an RMSE of 2.58 × 10−5 and an R2 of 0.982 for the testing dataset. According to the prediction result, the fourth aquifer after grouting in the 85 mining district is divided into five water abundance zones. The strong and medium–strong water abundance zones are mainly distributed in the study area’s eastern region. A small portion of them is distributed in the northwestern and northern areas. This study provides a new insight for predicting the water abundance of thick loose aquifers and a theoretical basis for safe mining under thick loose aquifers.

Investigating the effect of gravity on the flow characteristics of granular materials is crucial for a deeper understanding of geological hazards on Earth and other celestial bodies. This research employs discrete element numerical simulation methods to systematically analyze the dynamic process of granular system collapse and flow under varying gravity conditions. By analyzing the collapse initiation angle, flow velocity, and energy evolution of the granular system at different time intervals, the study reveals that as gravity increases, both the average flow velocity and the front velocity of the granular system significantly increase. After normalizing the particle flow velocity, the velocity curves converge, indicating that both the flow velocity and duration are proportional to gravity. Higher gravity levels accelerate the accumulation of kinetic energy in the granular system, but once the kinetic energy reaches its peak, its dissipation rate also increases significantly. The energy dissipation, horizontal displacement, and evolution time of the granular system exhibit a power-law relationship with gravity. This research provides significant scientific value for further understanding the collapse and flow characteristics of granular systems in geological hazards on Earth and other extraterrestrial bodies.

The mining of shallow coal seam groups triggers mine water inrush and ecological environment destruction. Effective groundwater prevention and control requires controlling the compaction and seepage characteristics (CSCs) of broken rock in goaf. In this study, the CSCs of roof lithology and goaf broken rock combinations are experimentally investigated. The results indicate that, for samples with identical gradation, the percentage of void (PV) is minimized in sandstone–mudstone combinations, while PV increases with higher coal content. Initial compaction of composite samples is primarily governed by soft rock re-crushing, whereas the stable compaction stage is determined by the initial PV. Under low axial stress, the CSCs of lithological combination samples exhibit instability, with the mudstone layer reducing flow velocity by approximately 36% under equivalent compaction and seepage conditions. Particle migration, leading to the blockage of the seepage section, is an important cause of the decrease in permeability. Based on experimental findings, a stress–void–seepage coupling model is established to describe the compaction–seepage behavior of lithologic combination broken rock in shallow goafs.

Faults are the primary drivers of earthquakes and exert a strong control on rupture mechanisms, earthquake magnitude, and the spatial distribution of coseismic landslides (CLs). However, how CL spatial distribution patterns vary with faulting style remains poorly constrained. Here, we compiled a catalog of CLs associated with 18 global major earthquakes (MW > 6.0) within continental regions since 1900 and explored the distribution patterns of CLs associated with the three major earthquake types: oblique-slip, dip-slip, and strike-slip. Our results reveal two distinct spatial distribution patterns of CLs: a hanging-wall distribution for oblique-slip and dip-slip earthquakes and a bell-shaped distribution for strike-slip earthquakes. The orientation of CLs is closely related to fault geometry and slip type. Specifically, in oblique-slip, strike-slip, and dip-slip earthquakes, CLs predominantly develop parallel, perpendicular, or perpendicular to the fault strike, respectively. In terms of slip rake, CLs are mainly aligned perpendicular, parallel, and parallel to the fault slip direction for oblique-slip, strike-slip, and dip-slip events, respectively. Importantly, the distribution patterns of CLs encode information about ground movement during an earthquake. While Peak Ground Acceleration (PGA) serves as an indicator of ground motion intensity, a comprehensive characterization of CLs—including their size and predominant movement direction—requires consideration of both the earthquake type and the local slope conditions.

This study addresses the issue of coordinated development of coal, oil, and gas resources in the Yulin-Shenmu Coalfield. Taking the 132,201 working face of the Xiaobaodang No. 1 Coal Mine as a case study, the study combines FLAC3D numerical simulation with on-site monitoring to analyze the impact of mining activities on the stability of gas well casings. Simulation results indicate that mining activities cause stress redistribution in the surrounding rock, with a maximum shear stress of 5.8 MPa, which is far below the shear strength of the casing. The maximum horizontal displacement of the wellbore is only 23 mm, with uniform overall deformation and no shear failure. On-site monitoring showed that the airtightness was intact, and the wellbore diameter test did not detect any destructive damage such as deformation or cracks. Concurrently, fiber optic strain monitoring of the inner and outer casings aligns with simulation results, confirming no significant instability caused by mining activities. The conclusion is that mining activities have a negligible impact on the stability of the gas well casing-concrete composite structure. The dual casing-cement ring structure effectively coordinates deformation to ensure safety. This finding provides a reliable technical basis for the coordinated exploitation of coal, oil and gas resources at the Xiaobaodang No. 1 Coal Mine and similar mines.

Driven by global climate change and the “dual carbon” goals, the efficient development and safe storage of deep carbon storage spaces have emerged as a critical pathway to achieve carbon neutrality. This paper systematically reviews the exploration technologies, site suitability evaluation methods, and key theoretical challenges for large-scale carbon storage in deep saline aquifers, depleted oil and gas reservoirs, unminable coal seams, and basalt formations. The study reveals that multiphysical field coupling effects (thermal-fluid-mechanical-chemical) induced by CO2 injection may trigger risks such as fault activation, caprock leakage, and seismic activity, necessitating the construction of a risk assessment framework through multiphysical field numerical simulation and dynamic monitoring. Deep saline aquifers account for 98.64% of China’s theoretical carbon storage potential, but their significant heterogeneity requires suitability evaluation that integrates geological stability (fault development, caprock sealing capacity) and storage capacity (porosity, permeability) to construct a multi-scale index system. Methods such as the analytic hierarchy process (AHP), GIS, and machine learning are combined to optimize site selection decisions. To address the complexity of deep carbon storage spaces, integrated seismic and electrical exploration technologies significantly improve reservoir identification accuracy: full-waveform inversion (FWI) characterizes pore-fracture structures, gravity-magnetic inversion constructs deep structural models, and multiphysical data fusion reduces the non-uniqueness of inversion results. In the context of green transformation in coal mines, the innovative “negative carbon backfilling” technology is proposed: CO2 is used to mineralize industrial solid wastes such as steel slag and fly ash to prepare backfilling materials, achieving high carbon sequestration rates while balancing ecological restoration and dynamic disaster prevention. The synergistic effect of CO2 storage in deep unminable coal seams and enhanced coalbed methane (ECBM) recovery is significant, requiring optimization of the full-life-cycle management model for “fracturing-displacement-storage”. CO2 storage in goafs faces challenges from the complex seepage-adsorption mechanisms in fractured coal-rock masses, necessitating the development of multiphase dynamic models to assess storage potential in free, adsorbed, and dissolved states. Potential calculation methods vary significantly by reservoir type: Saline aquifers use the storage mechanism method (coupling structural trapping, dissolution, and mineralization), depleted oil and gas reservoirs combine material balance methods with numerical simulation, and coal seams rely on adsorption capacity and displacement efficiency evaluations. In terms of injection technology innovation, micro-nano bubble injection enhances CO2 dissolution rates, while the “water-mixed dissolved-state injection” mode in basalt formations achieves high mineralization rates. Future research must emphasize interdisciplinary integration: Developing intelligent multiphysical field exploration and fine imaging to overcome challenges in detailed characterization of multi-type three-dimensional carbon storage spaces; researching and developing high-efficiency deep negative carbon backfilling materials and technical equipment; and constructing a comprehensive system for calculating CO2 storage potential and evaluating suitability in deep integrated three-dimensional spaces, form technical standard systems and information decision-making platforms, and provide theoretical and engineering support for large-scale geological storage under the “dual carbon”goals.