The article examines the comprehensive features of contour blasting technology in tunnel construction and excavation works during underground mining development operations. The main disadvantages of conventional blasting methods are analyzed in detail, including excessive disruption of rock mass integrity, formation of extensive fractured zones around excavations, significantly increased support costs, reduced structural stability, and compromised work safety conditions. The substantial advantages of contour methods are highlighted, including effectively minimizing rock contour damage, dramatically improved excavation surface quality, reduced overbreak volumes, substantial savings in support materials, enhanced excavation precision, and improved overall project economics. A comprehensive mathematical model is presented for calculating optimal spacing between blast holes, considering explosive properties, dynamic characteristics of rocks being excavated, geomechanical parameters of the rock mass, stress distribution patterns, and local geological conditions. Modern contour blasting methods are thoroughly analyzed, including pre-splitting techniques, smooth blasting procedures, controlled blasting approaches, and their various combined variants tailored to specific geological formations. Key technological parameters are systematically determined: optimal borehole diameter, precise charge spacing calculations, appropriate linear charge mass distribution, suitable explosive type selection, advanced initiation system design, timing sequence optimization, and burden-to-spacing ratios. Detailed practical recommendations are provided for applying contour blasting methods under various challenging geological conditions, including hard crystalline rock formations, medium-strength sedimentary rocks, fractured rock masses, and weak soil conditions. Quality control issues and comprehensive effectiveness evaluation of contour blasting methods in complex underground conditions are thoroughly considered. The research addresses systematic optimization of blasting parameters through extensive field testing, continuous monitoring of excavation quality indicators, vibration control measures, and post-blast damage assessment protocols. Special attention is given to advanced safety measures, environmental impact considerations, noise control, and dust management when implementing sophisticated contour blasting technologies in underground mining operations and modern tunnel construction projects.

During coal mining, the development of joint fractures in overlying rock strata is one of the key factors that degrade the mechanical properties of rock masses, form water-conducting fracture zones, and induce safety hazards. To investigate the fracture evolution characteristics of overlying strata during coal extraction under thick and hard roof conditions, this study established a mining physical model based on similarity simulation technology, tracked the fracture evolution process, and performed quantitative analysis using fractal theory. The results show that fracture development is significantly correlated with the mining advance distance: the fractal dimension of fractures is small in the initial mining stage and gradually increases as the working face advances. When the mining width exceeds the ultimate span of the roof, local fractures expand rapidly with a sharp rise in the fractal dimension to 1.436; further increasing the mining width triggers large-scale sudden fracture expansion, resulting in severe degradation of rock mass integrity, with the maximum fractal dimension reaching 1.445. The research findings provide theoretical references for safety management and disaster prevention in coal mining under thick and hard roof conditions.

Research on the predicted height of water-conducting fracture zones based on the BO-RFR model and SHAP analysis.

To accurately analyze the time-dependent stability of large-span tunnels traversing the F2 fault fracture zone, this study focused on the deep-buried red-bed mudstone of the Jishan Tunnel. Rock cores were retrieved from the critical Grade V surrounding rock section (depth 370 m). Uniaxial and triaxial compression tests were conducted to determine basic mechanical parameters. Through step-loading creep tests, the creep characteristics were analyzed, and a long-term strength of 19.2 MPa was identified. Analysis revealed that the deformation aligns well with the stress-dependent Burgers model, where parameters evolve with stress level. Using the Levenberg–Marquardt algorithm, the variable model parameters were derived. Finally, three-dimensional creep parameters were obtained for numerical validation. Engineering recommendations for support timing and yielding mechanisms are proposed to mitigate rheological risks in fault-affected zones.

Ground subsidence in mined-out areas has irreversible impacts on residents’ lives and infrastructure, making its monitoring and prediction crucial for ensuring safety, protecting the ecological environment, and promoting sustainable development. This study employed the Small Baseline Subset Interferometric Synthetic Aperture Radar (SBAS-InSAR) technique to process Sentinel-1A satellite images of Liaoyuan’s Northern New District from August 2022 to March 2025, deriving ground deformation data. The SBAS-InSAR results were validated using unmanned aerial vehicle (UAV) measurements. Monitoring revealed deformation rates ranging from −26.80 mm/year (subsidence) to 13.12 mm/year (uplift) in the area, with a maximum cumulative subsidence of 59.59 mm observed near the Xi’an Sixth District. Based on spatiotemporal patterns, most mining-induced subsidence in the study area is in its late stage, primarily caused by progressive compaction of fractured rock masses and voids within the collapse and fracture zones. Using subsidence data from August 2022 to March 2024, three prediction models—LSTM, GRU, and TCN-GRU—were trained and subsequently applied to forecast subsidence from March 2024 to August 2025. Comparisons between the predictions and SBAS-InSAR measurements showed that all models achieved high accuracy. Among them, the TCN-GRU model yielded predictions closest to the actual values, with a correlation coefficient exceeding 0.95, validating its potential for application in time-series settlement monitoring.

Focus on the toxicology of deep-sea mining: Biotoxicity of heavy metals to Vibrio fischeri released from disturbed surface sediments of the western Clarion-Clipperton zone, Pacific Ocean.

Abyssal macrofaunal community structure in the eastern Clarion-Clipperton Fracture zone

Failure mechanisms of fault fracture zone under dynamic loading

The two-dimensional Electrical Resistivity Imaging (ERI) technique was used in this study to investigate The variations in resistivity within the Hit-Kubaisa area, Abu Jir Fault Zone (AJFZ) to detect fractures zone and evaluation of this technology in detecting faults. The study also aims to analyze the impact of these fractures on the geology of the region. Using the Wenner-Schlumberger array, the researchers conducted four survey lines with 120 electrodes spaced 10 meters apart, allowing them to map subsurface geological structures down to a depth of 240 meters. The results showed clear differences in resistivity, making identifying fracture zones and potential subsurface cavities possible. It also highlighted how these faults affect the sedimentary layers, especially the differences in the thickness of the Euphrates Formation and the absence of the Ana Formation.

During the high-intensity mining of shallow-buried thick coal seams, the formation of a water-conducting fracture zone within the overburden is a primary cause of damage to the groundwater system. To address the challenge of balancing efficiency and cost in traditional water-retaining mining methods, this study proposes and validates a trapezoidal strip filling mining technology based on the “span reduction effect”. By developing a mechanical model of a four-sided simply supported thin plate representing the key layer, the fundamental mechanism of the filling body was elucidated. This mechanism involves the active adjustment of the support boundary, which effectively reduces the force span of the key layer. Furthermore, leveraging the fourth-power relationship (w ∝ a4) between deflection and span, the bending deformation of the overburden rock is exponentially mitigated. This study employs a four-tiered integrated verification system comprising theoretical modeling, physical simulation, numerical simulation, and engineering field testing: First, theoretical calculations indicate that reducing the effective span of the key layer by 40% can decrease its maximum deflection by 87%. Second, large-scale physical similarity simulations predict that implementing this filling method can significantly control the height of the water-conducting fracture zone, reducing it from 94 m under the collapse method to 58 m, which corresponds to a 45.5% reduction in surface settlement. Third, FLAC3D numerical simulations further elucidated the mechanical mechanism by which the backfill system transforms stress distribution from “coal pillar-dominated bearing capacity” to “synergistic bearing capacity of backfill and coal pillars”. Shear failure in the critical layer was suppressed, and the development height of the plastic zone was restricted to approximately 54 m, showing high consistency with physical simulation results. Finally, actual measurements of water injection through the inverted hole underground provide direct evidence: The heights of the water-conducting fracture zones in the filling working face and the collapse working face are 59 m and 93 m, respectively, reflecting a reduction of 36.6%. Based on the consistency between measured and simulated results, the numerical model employed in this study has been effectively validated. Research indicates that employing trapezoidal strip filling technology based on principal stress dynamics regulation can effectively promote a shift in the failure mode of the overlying critical layer from “fracture–conduction” to “bending–subsidence”. This mechanism provides a clear mechanical explanation and predictable design basis for the green mining of shallow coal seams.

A comprehensive study on the distribution characteristics and exploitation strategies of remaining oil was carried out in the Ordovician ultra-deep fault-controlled fractured–vuggy carbonate reservoir within the Shunbei No. 1 strike–slip fault zone. This research addresses challenges such as severe watered-out and gas channeling encountered during multi-stage development, marking a shift toward a development phase focused on residual oil recovery. By integrating seismic attributes, drilling, logging, and production performance data—and building upon previous methodologies of “hierarchical constraint and genetic modeling”—a three-dimensional geological model was constructed with a five-tiered architecture: strike–slip fault affected zone, fault-controlled unit, cave-like structure, cluster fillings, and fracture zone. Numerical simulations were subsequently performed based on this model. The results demonstrate that the distribution of remaining oil is dominantly controlled by the coupling between key geological factors—including fault kinematics, reservoir architecture formed by karst evolution, and fracture–vug connectivity—and the injection–production well pattern. Three major categories with five sub-types of residual oil distribution patterns were identified: (1) local low permeability, weak hydrodynamics; (2) shielded connectivity pathways; and (3) Well Pattern-Dependent. Accordingly, two types of potential-tapping measures are proposed: improve well control through optimized well placement and sidetrack drilling and reservoir flow field modification via adjusted injection–production parameters and sealing of high-permeability channels. Techniques such as gas (nitrogen) huff-and-puff, gravity-assisted segregation, and injection–production pattern restructuring are recommended to improve reserve control and sweep efficiency, thereby increasing ultimate recovery. This study provides valuable guidance for the efficient development of similar ultra-deep fractured–vuggy carbonate reservoirs.

This study introduces a novel maximum plastic zone fracture criterion to investigate the fracture behaviour of rock bridges under compression. The proposed criterion quantifies the plastic zone dimensions at crack tips to determine the initiation and propagation of wing cracks, with the overall fracture process characterised by the evolution of the plastic zones. The influence of multi-crack interactions on wing cracks propagation is further examined, and a recommended range of correction factors for stress intensity factors (SIF) is provided. Subsequently, theoretical analyses are conducted on three specimens containing two parallel pre-existing cracks of equal length to the rock bridge. Results reveal that the distribution of pre-existing cracks significantly affects the fracture rate and mode of rock bridges, whereas the underlying failure mechanism remains consistent, primarily governed by the continuous propagation of wing cracks leading to plastic yielding throughout the rock bridge region (RBR). Furthermore, numerical simulations using PFC 2D show good agreement with the theoretical predictions, validating the proposed criterion and providing deeper insight into the fracture evolution of rock bridges.

The tunnel boring machine (TBM) is a core equipment for mountain tunnel engineering, but it often faces problems such as surrounding rock deformation, collapse, and TBM entrapment when crossing fault fracture zones. Taking the TBM crossing of F1 fault in the Pilot Tunnel of Daliangshan No.1 Tunnel as the engineering case, this study adopted a combined method of laboratory tests, numerical simulation, and field monitoring to clarify the deformation characteristics of surrounding rock during TBM's passage through the fault fracture zone, and proposed and verified effective reinforcement measures. The results show that the tunnel deformation in the F1 fault zone presents a "larger in the middle and smaller at both ends" pattern. When tunneling reached the fault core area, the maximum vertical vault settlement was 92 mm and the maximum ground settlement was 42 mm, with the vault settlement response occurring earlier than the sidewall springline deformation. Away from the fault zone, the stress release of surrounding rock stabilized, with a settlement increment of less than 5 mm. The comprehensive reinforcement system proposed for problems such as fractured surrounding rock in the fault zone and insufficient gripper shoe bearing capacity achieved remarkable effects. After reinforcement, the maximum vertical vault settlement and ground settlement of all monitored sections were reduced to approximately 17 mm and 7 mm, respectively, decreasing by 79.3% and 83.3% compared with those before reinforcement. This effectively mitigated construction risks and ensured continuous TBM advancement. The research findings can provide data support and technical reference for TBM construction in mountain tunnels under similar "weathered rock + fault fracture zone" conditions.

With the continuous increase in coal mining depth and intensity, the stress distribution in surrounding rock during multi-working face coordinated mining has become increasingly complex, significantly affecting the safe and efficient extraction of coal resources. This study takes the 22,214 and 22,215 working faces in Liuta Mine as the engineering background and employs FLAC3D numerical simulation to analyze the evolution of mining-induced stress and overburden fracture characteristics during coordinated mining of two adjacent faces. By establishing the stress superposition intensity index I σ and the plastic zone evolution index I P , the mechanisms of stress superposition and cumulative plastic damage in multi-working face mining were quantitatively revealed. Simulation results indicate that the stress and plastic zone in the first-mined face exhibit a symmetric distribution, with the peak abutment pressure increasing as the face advances, reaching a maximum stress concentration factor of 1.8. In contrast, the subsequent face, influenced by the adjacent goaf and the coal pillar and key stratum structure, shows significant asymmetry in both strike and dip stress distributions. The stress concentration factor on the coal pillar side reaches a maximum of 2.3, and the stress increment within 0–40 m ahead of the face is approximately 1.3–1.4 times that of the first-mined face. The multi-working face advance process demonstrates a three-stage evolution characterized by low superposition, medium superposition, and strong superposition. At an advance distance of 2,400 m, corresponding to the transition of the main key stratum from a suspended state to a fractured voussoir beam structure, the stage represents a strong superposition zone of stress and plastic deformation. In this zone, the plastic area on the coal pillar side connects with the goaf of the first-mined face, leading to a significant increase in the risk of surrounding rock instability. The study elucidates the mechanisms of stress transfer and plastic zone interconnection during coordinated multi-working face mining and identifies the strong superposition stage as a critical period for rockburst prevention and control. Accordingly, a combined strategy of differentiated support and directional pressure relief is proposed to maintain surrounding rock stability, with emphasis on monitoring the strong plastic deformation superposition zone. The findings provide a theoretical reference for mining-induced stress analysis, stability control of surrounding rock, and rockburst prevention under similar geological and mining conditions.

Pediatric olecranon fractures are uncommon periarticular injuries with unclear treatment guidelines for varying magnitudes of intra-articular displacement. Similar to other pediatric elbow fractures, minimally displaced fractures are treated nonsurgically, and potential for further displacement following nonsurgical treatment exists. This study assesses the incidence and risk factors for further displacement after nonsurgical treatment of minimally displaced pediatric olecranon fractures. A retrospective review was conducted on patients aged 0 to 15 years with isolated olecranon fractures treated nonsurgically at a single institution. Radiographic measurements of intra-articular and nonarticular displacement on lateral views were collected with follow-up imaging done until confirmed radiographic union. Patients with more than 1-mm change in displacement on the articular side during treatment were identified. Fractures were classified at specified locations, including zone 1 (proximal 1/3), zone 2 (middle 1/3), and zone 3 (distal 1/3). A total of 64 patients met inclusion criteria, 42 (65.6%) were males, and the average age at injury was 8.25 years. Casting without closed reduction was the definitive treatment method in 59 patients (92.2%). Of the fractures observed, 30 (46.9%) occurred in zone 1, followed by 23 patients (35.9%) in zone 2 and 11 patients (17.2%) in zone 3. Interval displacement was seen in 14 patients at follow-up visits (21.9%) with greater body mass index observed in the redisplacement group (P = 0.053). Change in management was required in two patients (3.1%). Displacement of ≥1 mm at initial evaluation did not affect the rate of subsequent displacement at follow-up visit (P = 0.571). Neither fracture zone nor fracture configuration were statistically significant for change in fracture displacement. Further displacement was observed in 20% of minimally displaced olecranon fractures regardless of the zone and magnitude of initial displacement with a small percentage leading to a change in the management. Close radiographic follow-up for nonsurgically treated olecranon fractures is recommended.

This study aims to address the critical challenge of the formation of acid mine drainage (AMD) in coal mining areas by systematically investigating groundwater recharge pathways and developing targeted source reduction strategies. A range of methods were employed, including field investigations, surveying and mapping, in situ measurements of hydraulically conductive fracture zones (HCFZs), spatial and hydrological analyses, yielding multi-source data. Based on the comprehensive dataset obtained, a novel methodology was developed to identify surface water infiltration pathways. Downhole video monitoring results indicate that the advancements in coal mining technology have gradually increased the heights of HCFZs. Furthermore, mining-induced fissures in hard rock layers were found to extend further vertically and form dense, interconnected networks, leading to higher permeability coefficients compared to those in weak rock layers. Surface water preferentially infiltrates at intersections of HCFZs, coal seams, and topographic features. Notably, groundwater recharge in the goaves of the No. 10 coal seam primarily occurs along the paleo-valley system where natural drainage aligns with mining-induced fissures. This study provides an example of source reduction treatment for AMD in mining areas.Supplementary InformationThe online version contains supplementary material available at 10.1038/s41598-025-33612-4.

Predicting water-conducting fracture zone height in three-soft coal seams using a BOA-MLP model.

Tectonic fracturing and clay enrichment in basalt slip zones: A key factor of 2019 Shuicheng landslide in southwest China

Prediction and Interpretation on the Height of Water Conducting Fracture Zone in Coal Mining Based on Heuristic Ensemble Learning

Shaking table test on seismic response and failure characteristics of buried pipeline-tunnel structure crossing fault fracture zone