2026-04-01
Shixing Cheng, Zhanguo Ma, Yue Li, Xiao Zhang
The directional pre-splitting blasting has been widely utilized in coal mines, and the synergistic of shaped charge tube and empty hole helps form directional cracks and control crack length. This study used the dynamic numerical calculation method to investigate the influences of the uncoupling coefficient, the distance between empty hole and blasting hole, and the diameter of empty hole on the effective stress and crack propagation under the synergistic effect of shaped charge tube and empty hole. The formation, propagation, and crack arresting rule of the pre-splitting blasting crack were revealed. The non-penetrating crack directional control approach was proposed and applied in the deformation control practice of the small coal pillar roadway. During double-hole blasting, with the increase in the distance between empty hole and blasting hole, along with the diameter of empty hole, the four symmetric cracks around the empty hole change to bilateral symmetric ones. It was suggested to place the empty hole in the middle of the two blasting holes, and the crack arresting hole be arranged at the junction of the penetrating zone and the non-penetrating zone. Field application results showed non-penetrating cracks formed in the roof of the small coal pillar roadway. Compared with the roadway without pre-splitting, the increase in bolt axial force was small, with an average increase rate of 32.5%. The research results provide a basis for determining parameters of non-penetrating pre-splitting blasting.
DOI: 10.3389/feart.2026.18037752026-04-01
Renyi Wang, Jianghang Zhu, Yong He, Jiangtao Li, Jian Yan, Zhilong Chen, Dandan Yin
The classical Hjulström diagram is an empirical rule that qualitatively describes the relationship between flow velocity, particle size, and erosion–transport–deposition. It has long lacked a unified theoretical foundation, which limits the quantitative interpretation of nonlinear variations in these processes. To address this, we establish a unified analytical model for the critical mean flow velocities that govern erosion, transport, and deposition. The model is based on Yang Meiqing’s formula for critical bed shear stress, applicable to the full range of particle sizes, and the Ferguson–Church unified settling velocity formula. It incorporates the logarithmic velocity distribution law and uses the Rouse number as the critical deposition criterion. Theoretically, it demonstrates the U-shaped characteristic of the erosion zone, the “wide for fine and narrow for coarse” feature of the transport zone, and the convex curve of the deposition zone in double-logarithmic coordinates, thereby theoretically revising the traditional understanding in the classical Hjulström diagram that approximates the deposition boundary as a straight line. The correspondence between the unified analytical model and the classical Shields and Rouse theory, which can be regarded as a special case of this unified model under certain conditions, is further analyzed. By explicitly introducing the factors of riverbed inclination angle and water depth, the application scope of the Hjulström diagram is expanded, providing a reliable theoretical basis for quantitatively studying the erosion–transport–deposition relationship of river particles.
DOI: 10.3389/feart.2026.17911252026-03-31
Sacit Mutlu
The right-lateral Hasan Timur Lake Fault (HTLF), located approximately 40 km east of Lake Van, remains geomorphologically under characterized despite its influence on regional drainage and landscape evolution. The study area represents an active morphotectonic setting developed under strike-slip fault control, characterized by segment-scale morphological differentiation and a drainage network organized parallel to the fault trace. This study evaluates along-strike variability in surface responses using a multi-index morphometric framework. A 30 m digital elevation model (DEM) was analyzed through a GIS-based workflow implemented in ArcGIS Pro and integrated with MATLAB/TecDEM to derive key geomorphic indices, including the stream length–gradient index (SL), mountain-front sinuosity (Smf), valley floor width-to-height ratio (Vf), hypsometric integral and curves (HI–HE), and basin asymmetry factor (AF), for 78 fault-influenced micro-basins. The morphometric results reveal systematic spatial variations in basin geometry and drainage organization along the fault. S-shaped hypsometric curves characterize an intermediate stage of landscape development, reflecting the coupled effects of tectonic perturbation and fluvial erosion. In contrast, the concentration of convex hypsometric curves adjacent to the fault trace particularly in the southeastern sector indicates enhanced incision and geomorphic rejuvenation. Basin asymmetry patterns show a prevailing downstream leftward tilting in the northwestern and southeastern sectors, with localized rightward deviations in the central sector, suggesting spatially variable deformation reflected in basin-scale surface morphology. SL values in the southeastern sector, together with low Smf values and predominantly low Vf ratios, indicate steeper gradients, narrow valley floors, and straighter mountain fronts, collectively pointing to stronger geomorphic disequilibrium in this sector. These observations identify the southeastern segment of the HTLF as the most dynamically evolving part of the landscape.
DOI: 10.3389/feart.2026.18043372026-03-26
Wanyuan Nie, Taihua Wang, Kai Li, Jiaxing Liu
Low and ultra-low permeability sandstone reservoirs are widely developed in Xinjiang, China and represent important targets for maintaining oilfield production and enhancing oil recovery. However, strong reservoir heterogeneity and poor pore structures severely limit the effectiveness of conventional development methods. Field practice and previous studies indicate that the applicability of pressure-driven techniques varies markedly among different low and ultra-low permeability sandstone reservoirs, and the lack of reliable criteria for block selection has become a key constraint on large-scale application. Based on laboratory experiments, numerical simulations, and field case analyses, this study elucidates the key controlling factors governing pressure-driven performance, clarifies the geological conditions favorable for effective implementation, and develops an applicability evaluation framework for pressure-driven development in low and ultra-low permeability sandstone reservoirs. The results demonstrate that pressure-driven applicability is jointly controlled by rock mechanical properties and flow capacity, with elastic modulus and permeability identified as the dominant controlling factors. Pressure-driven techniques exhibit optimal performance in low-to-moderate permeability reservoirs, whereas their effectiveness is limited under ultra-low permeability conditions and diminishes in relatively higher-permeability reservoirs. On this basis, an evaluation index system incorporating indicators related to microfracture generation, reservoir stimulation and volumetric expansion behavior, and reservoir petrophysical properties is established, and the Analytic Hierarchy Process is employed to determine indicator weights. Application of the proposed framework to typical blocks and the study area shows that evaluation scores are in good agreement with actual field performance and effectively distinguish pressure-driven applicability among different blocks. Among the evaluated blocks, the M2 block exhibits the most favorable combination of rock mechanical properties, flow capacity, and reservoir scale parameters, making it the optimal target for pressure-driven development in the study area. The proposed framework provides a quantitative basis for pressure-driven technology selection and deployment in low and ultra-low permeability sandstone reservoirs in Xinjiang.
DOI: 10.3389/feart.2026.18012612026-03-25
He Zhang, Hongfeng Lu, Hui Diao, Changwen Xiao, Lingxiu Jiang, Jidong Yuan, Runbo Hao, Zhenglong Jiang
IntroductionOrganic matter enrichment in the source rocks of rift lacustrine basins is crucial for the formation of oil and gas, and sedimentation rates and sedimentary environments are two important factors influencing organic matter enrichment.MethodsIntegrating organic geochemistry (TOC and rock pyrolysis), inorganic geochemistry (major and trace elements), and sedimentation rate reconstruction, this study investigates the organic matter enrichment of Eocene Wenchang and Enping source rocks in the Lufeng Sag, Pearl River Mouth Basin. A model of the organic matter enrichment of source rocks in the Lufeng Sag was established based on paleoclimate, sedimentary facies, and sedimentation rates.ResultsThe organic matter enrichment in the Lufeng Sag was primarily governed by the coupling of paleoclimate, sedimentary facies, and sedimentation rates.DiscussionDuring the deposition of the fourth member of the Wenchang Formation (E2wc4), strong fault activity and rapid tectonic subsidence maximized the accommodation and water depth, establishing a stable, reducing, semi-deep to deep lacustrine environment. This period, characterized by a warm and humid climate, facilitated high paleoproductivity. Specifically, the synergistic effect of high primary productivity and high sedimentation rates (>500 m/Ma, averaging 634.86 m/Ma) in the deep lacustrine facies led to the development of excellent source rocks with a mean TOC of 2.82 wt. %. In contrast, the shore-shallow lacustrine and braided river delta front, developed under moderate sedimentation rates (100-500 m/Ma) and weakly reducing conditions, yielded good to average source rocks. During the subsequent decline phase (Enping Formation), weakened tectonism and an arid climate resulted in shallow, oxidized water bodies and lower productivity, significantly diminishing the organic matter preservation potential. Overall, the combination of a warm-humid climate, high sedimentation rates, and a strongly reducing environment during the intensive rifting stage provided the most favorable conditions for high-quality source rock formation.
DOI: 10.3389/feart.2026.17637552026-03-25
Fang Yuan
IntroductionIn order to address the challenges of strong spatiotemporal heterogeneity, lack of physical constraints, and insufficient evolutionary continuity in multi-source geological data, this paper proposes a physical constraint graph spatiotemporal transformer inversion framework.MethodsBased on the mechanism of geomechanics, this paper applies the theory of elastic dislocations and the equation of fault sliding, and takes the Feidong area of Anhui Province as an example to unify the spatiotemporal and feature encoding of InSAR (interferometric synthetic aperture radar)/GNSS (global navigation satellite system) deformation, remote sensing/digital elevation models, and drilling multimodal data in this area, and aggregates them into a dynamic map with fault segments as nodes, constructing a graph spatiotemporal transformer model.ResultsThe results indicate that the proposed model achieved a Kendall tau-b coefficient of 0.811 in terms of spatiotemporal consistency; a global intersection of 0.741 was achieved in the spatial distribution of the fault zone; in terms of geological interpretability, the average multi-scale feature matching of this model was 0.855.DiscussionThe spatiotemporal consistency and geological interpretability of this model in fault activity inversion are superior to baseline models using ST-GCN (Spatiotemporal Graph Convolutional Network), Physical Information Neural Network, and CNN LSTM (Convolutional Neural Network Long Short Term Memory Model). The conclusion indicates that this method is helpful in reconstructing the evolution of fault activity in the Feidong area, providing a new approach and reference for multimodal data fusion and intelligent analysis of complex fault systems.
DOI: 10.3389/feart.2026.1753000