Against the backdrop of sustained growth in China’s energy demand and the progressive exhaustion of coal resources in eastern mining districts, coal-bearing regions in Northwest China are assuming an increasingly important role in maintaining long-term energy supply stability. Nevertheless, coal extraction in this region is inherently constrained by fragile geological settings, which pose fundamental challenges to large-scale, deep, and long-duration mining activities. As mining disturbances accumulate over time, tensions between coal exploitation and the regional geological-environmental system continue to intensify. In this context, this study focuses on the coupled responses of key Earth system components, including the lithosphere, hydrosphere, ecosphere and atmosphere, to coal mining disturbances. Drawing on the conceptual framework of Earth system science, geological safeguard requirements and implementation pathways for loss-reducing coal mining are proposed. First, it provides an in-depth analysis of the effects of coal mining on Earth's multi-spheres and clarifies the relationship between Earth system science and coal mining. Second, from the perspectives of Earth system science, such as holism, dynamism, quantification, and systematization, it innovates the geological support requirements for low-impact coal mining in terms of geological survey methods, evaluation of geological elements, evolution of geological conditions, and sustainable development of geological resources. Finally, by integrating multi-scale and multi-approach exploration and observation technologies, a geological survey method and a three-dimensional dynamic monitoring model covering the entire coal mining lifecycle are established. Utilizing massive, multi-source, and diverse measured data, a multi-sphere coupling model is constructed to quantitatively analyze the dynamic evolution of geological elements during coal mining, thereby building a supply-side-guided guarantee system for minimizing mining-induced damage. From a methodological standpoint, Earth system science offers an effective framework for interpreting the interconnected responses of multiple Earth system components induced by coal mining, while mining activities provide a natural laboratory for exploring multi-sphere coupling mechanisms. Geological safeguard research for loss-reducing coal mining therefore necessitates a fundamental paradigm shift from traditional practices characterized by static assessments, segmented stages, experience-based judgments, single-sphere isolation, and production-oriented priorities to an integrated approach centered on process-based dynamics, quantitative geological characterization, multi-sphere coupling, and sustainability considerations. To support this transition, a comprehensive geological safeguard system is proposed, incorporating an integrated "space-air-ground" monitoring network, quantitative models describing cross-sphere interactions, and supply-side driving mechanisms. This system is intended to enable a full life-cycle framework for loss-reducing coal development, extending from precise early warning of mining-induced risks to diversified utilization of resources and products after mine closure. This research provides important theoretical support for achieving green mining of coal resources and holds significant practical value for the implementation of strategic national energy policies in the northwest region.

In recent years, the significant increase in land resource demands in loess gully regions has led to rapid development of fill engineering projects, accompanied by increasingly prominent landslide hazards. While altering the original topography, these projects substantially modify the stress state of soil mass, with moisture content and confining pressure fluctuations becoming critical factors affecting slope stability. This study focuses on a loess-filled slope in Tianshui City, conducting a series of triaxial creep tests under controlled moisture content and confining pressure. The results demonstrate: ① Increased moisture content weakens soil structure and reduces soil strength, while higher confining pressure restricts lateral deformation. ② During moisture content elevation, the failure mode transitions from brittle fracture to plastic bulging (notably at 24% moisture content), with significantly increased axial compression. ③ Moisture content increase elevates pore water pressure, shifting the Mohr circle leftward; meanwhile, long-term creep effects reduce shear strength through decreased effective stress and moisture-induced cementation weakening, triggering shear failure when the Mohr circle boundary exceeds the new strength threshold. ④ Although confining pressure enhances long-term soil strength, stress redistribution in actual projects causes shear stress concentration at the slope toe as fill height increases, ultimately reducing slope stability. This study systematically reveals the creep behavior, failure characteristics, and stress evolution of filled slopes under varying moisture content and confining pressure conditions, providing experimental references and theoretical foundations for stability control in loess-filled engineering projects.

To elucidate the mechanical and seepage properties of typical Yan'an loess at different burial depths and its microstructural evolution patterns, this study systematically investigates four in situ loess layers (L₁–L₄) from a representative profile in Fuxian County, Yan'an. The objective is to clarify the synergistic mechanism of “structural densification–strength enhancement–permeability reduction,” providing scientific basis for regional loess stratum stability assessment and impermeability reinforcement design. Systematic investigations were conducted on the four loess layers using direct shear tests, permeability tests, and scanning electron microscopy (SEM) analysis. Pore parameters were quantitatively extracted using Avizo software. Data coupling analysis was performed via Pearson correlation analysis and principal component analysis (PCA). Results indicate: ① Shear strength exhibits a layered pattern with burial depth, showing significantly increased cohesion and a slight decrease in internal friction angle. ② The permeability coefficient decreases significantly with depth, exhibiting a “permeable upper layer, dense lower layer” characteristic, plummeting from 17.79×10⁻⁵ cm/s in Layer L₁ to 7.55×10⁻⁵ cm/s in Layer L₄. ③ At the microstructural level, particle contact patterns change from point contact and weak cementation in shallow layers to surface contact and strong cementation in deeper layers. Pores evolved from large pores (>35 μm) to medium-small pores (<30 μm), with shapes tending toward roundness. The orientation shifted from vertical dominance to uniform distribution. ④ Pearson analysis indicates a significant positive correlation between dry density and cohesion, while showing significant negative correlations with total pore area and permeability coefficient. PCA analysis reveals PC1 (contribution rate 70.8%) as the primary factor governing “structural densification-strength enhancement,” clearly distinguishing sample distributions between L₁ (loose, high permeability) and L₄ (dense, low permeability) layers. Conclusions indicate that the evolution of physical and mechanical properties in Yan'an loess is jointly governed by compaction and microstructural remodeling. With increasing burial depth, loess undergoes a “compaction-remodeling-densification” process: particles become more tightly packed, contact modes shift to surface contact, and large pores are compressed and destroyed, replaced by medium and small pores. Macro-scale manifestations include increased cohesion and significantly reduced permeability. Dry density, cohesion, and pore characteristics collectively govern the overall evolutionary trend of loess from loose and highly permeable to dense and low-permeability.

The superimposed effects of extreme rainfall events and engineering disturbances in the Loess Plateau have led to a significant increase in the risk of shallow loess landslides. This situation reveals the engineering governance contradiction of "ecological improvement vs. disaster intensification" in ecological restoration projects. This study focuses on the mechanical properties of the root-soil interface of Robinia pseudoacacia. Through methods including in-situ testing, single shear test, and theoretical analysis, we systematically quantified the multi-field coupling effects of moisture content fluctuations, root topological types, and variations in root content on the shear strength evolution of the root-soil interface. The results indicate: ① Vegetation roots in the shear strength characteristics of the root-soil interface. The shear process can be divided into three stages: initial linear elastic deformation, damage accumulation, and progressive failure. ② The stress-strain curves of the root-soil interface can be categorized into softening and hardening types, with the softening type comprising a strength-increasing phase followed by a strength-decaying phase. ③ A predictive model considering the stress-strain softening of the root-soil interface was proposed, demonstrating favorable predictive performance. This research provides essential data and theoretical support for ecological restoration in rapid slope stability assessments that incorporate vegetation factors.

The seasonal rainfall leads to a frequent wet-dry cycle environment across the China Loess Plateau. This environment often aggravates foundation settlement and collapsible deformation in loess subgrades. This study investigates the coupling mechanism of microstructural damage and macro-deformation evolution under wet-dry cycles. The findings provide a theoretical basis for engineering disaster prevention in loess regions. Artificially structured loess with controllable composition and uniform structure was prepared to simulate natural loess. This experimental approach facilitated the systematic study of the effects of wet-dry cycles (0～9 cycles) on loess. Macro-mechanical behaviors were tested using confined compression and single-line collapsibility methods. Microstructural characteristics were analyzed via Scanning Electron Microscopy (SEM), particle analysis, and X-ray Diffraction (XRD). The test results indicate that wet-dry cycling causes irreversible damage to the loess microstructure. Macroscopically, compressive deformation shows a significant positive correlation with the number of cycles. Conversely, the collapsibility coefficient follows a non-monotonic evolutionary pattern, first increasing and then decreasing. The structural parameters exhibit a non-linear decay characterized by an "initial sharp drop followed by stabilization". The first three cycles constitute the primary structural damage phase; the decay rate slows down significantly during cycles 5 to 9, reaching only about one-quarter of the initial rate. Microscopically, the dissolution and loss of cementing agents cause the soil structure to evolve. The support system transforms from a "strong cementation-large aggregate" structure to a "weak cementation-loose particle" contact system. This loss of cementing agents and the resulting microstructural rearrangement are the essential causes of macroscopic mechanical degradation. In the initial cycles, structural disintegration driven by cementation failure dominates. This significantly enhances collapsibility sensitivity. In later cycles, pore compaction and structural reorganization increase the soil's resistance to further deformation. Therefore, engineering practices must prioritize waterproofing during the early exposure period of the foundation to prevent sudden settlements caused by accumulated structural damage.

The study of the wetting-induced deformation mechanism of loess is of great importance for engineering disaster prevention and control in the Loess Plateau region. This research focuses on the Q₃p and Q₂p loess from Fuxian County, northern Shaanxi, aiming to reveal the deformation behavior and underlying mechanisms of loess from different geological eras under wetting conditions. A comparative study of the engineering properties of the two types of loess was systematically conducted through a series of physico-mechanical tests, mineral composition analysis, scanning electron microscopy (SEM) observations, and multi-condition consolidation-collapse tests. The results indicate that the consolidation deformation process of both types of loess can be divided into three stages: slow deformation under low pressure, accelerated deformation under medium pressure, and stabilized deformation under high pressure. Under high pressure conditions, the consolidation deformation becomes more sensitive to changes in initial water content. With increasing initial water content, the compression deformation of the Q₃p specimens intensifies significantly, while that of the Q₂p specimens weakens. In collapse tests, the two groups exhibited fundamentally opposite deformation characteristics: the Q₃p specimens showed typical collapse behavior, with the collapse coefficient initially increasing and then decreasing with rising pressure, whereas the Q₂p specimens displayed certain expansion characteristics. As the initial water content increased, the collapse coefficient of the Q₃p specimens gradually decreased, while the expansion tendency of the Q₂p specimens also weakened. Microstructural analysis revealed that the stability of the loess microstructure, particularly the presence of large pores, provides the necessary space for compression and collapse deformation. Mineral composition analysis indicated that the dissolution of soluble salt minerals (e.g., calcite) exacerbates soil compression and collapse deformation, while the water-absorbing expansion of clay minerals (e.g., illite) partially suppresses these behaviors. This study elucidates the controlling mechanism of the coupling effect between mineral composition and microstructure on the wetting-induced deformation behavior of loess, providing important theoretical support and practical guidance for engineering construction and geohazard mitigation in loess regions.

As the core node of the "belt and road" Central Asia land route, the engineering geological stability of Ili region in Xinjiang is crucial to regional development. The mechanical properties of Quaternary loess, which is widely distributed in the region, are continuously deteriorated under the complex climatic conditions such as seasonal freeze-thaw, dry wet cycle, heavy rainfall and the continuous effect of engineering activities, thus inducing frequent regional loess landslides. Therefore, it is of practical significance to further study the effect of freeze-thaw-wetting-drying (FTWD) cycle on the mechanical properties and nonlinear degradation law of Ili remolded loess. Based on the consolidated undrained triaxial shear test and microscopic test under FTWD cycle, the stress-strain response, strength parameter evolution and damage mechanism were revealed from the macro and micro scale. On this basis, assuming that the micro element strength of loess obeys the Log-logistic distribution function, the damage model of loess is established and its applicability is verified. The results showed that the shear strength decreased by 22.9% with the increase of the number of cycles, and the cohesion attenuation (45.2%) was significantly higher than the internal friction angle (7.27%). In the microscopic image, it can be seen that the compacted loess presents the characteristics of aggregate structure.The deviatoric stress-strain relationship curve of Ili loess sample is mainly strain hardening type. The cohesion of Ili loess decreases significantly with the increase of FTWD cycles, while the internal friction angle changes slightly. Combining the traditional Duncan-Chang model with the statistical damage theory, a constitutive model which can uniformly characterize the strain hardening and strain softening characteristics under different FTWD cycles is established, and the model parameters are solved. The model verification shows that it has good predictability for the test results under different confining pressures and cycles.

In order to study the soil-water characteristics and micro-mechanism of sulfate saline soil under freeze-thaw-salt coupling, the soil-water characteristic curves of saline soil with different salt content were tested and fitted with Gardner model, van-Genuchten model, and Fredlund-Xing model, and the microstructure and pore distribution characteristics of sulfate saline soil under freeze-thaw-salt coupling were analyzed. The results indicate that the volumetric water content of sulfate-salted soil decreases as matrix suction increases, with the resulting curves exhibiting a single-peak inverse ‘S’ shape. Notably, for a given volumetric water content, higher salt concentrations correspond to increased matrix suction. Freeze-thaw cycles promote the microstructural disintegration of the soil, leading to an increase in large pore volume and overall porosity. Following these cycles, both the matrix suction and volumetric water content of the soil samples decreased, causing the soil-water characteristic curve to shift leftward with an increasing number of freeze-thaw cycles.To evaluate the test results of saline soil, the G model, V-G model, and F-X model were employed. The F-X model exhibited a low fitting correlation coefficient, while the V-G model demonstrated poor fitting in both high and low suction phases. In contrast, the G model provided an overall good fitting performance. The microstructural changes in soil samples resulting from freeze-thaw actions are critical factors contributing to the reduction of the soil's water-holding capacity. The progressive development of pores and fissures in the samples, influenced by freezing, thawing, and salinity, facilitates the migration of water equilibrium.

Although certain achievements have been made in desertification control in China, the fragile ecological attributes of sandy lands have not been fundamentally altered. This study systematically investigates the bio-reinforcement mechanism and engineering applicability of desert sand based on Enzyme-Induced Calcium Carbonate Precipitation (EICP) technology using soybean urease. Through regulating soybean powder solution concentration, standing time, temperature, and pH, we revealed the regulation mechanism of urease activity. Single-factor experiments with varying enzyme-to-gelatin ratios, cementing solution concentrations, and spraying volumes of reaction solution were conducted to examine their effects on surface strength, calcium carbonate content, and cured layer thickness of desert sand. Finally, water retention tests were performed to evaluate the application performance of EICP-treated aeolian sand. Results demonstrate that soybean powder concentration, temperature, and pH significantly influence urease activity, with maximum activity achieved at 100 g/L soybean powder concentration, 45°C, pH=7, and 12 hour standing time. The effects of enzyme-to-gelatin ratio and cementing solution concentration on reinforcement indicators (surface strength, CaCO₃ content, cured layer thickness) followed an initial increase followed by decrease pattern, peaking at enzyme-to-gelatin ratio 1∶1, cementing solution concentration 1.25 mol/L, and reaction solution spraying volume 5 L/m². Water retention tests revealed that cementing solution concentration and spraying volume are critical factors in controlling CaCO₃ crystal formation to fill sand particle pores, achieving maximum water retention enhancement of 42% and significantly inhibiting water evaporation.

With the promotion of the national policy of developing the western region, the shortage of building materials in the surrounding areas of the northwest desert in China has become increasingly severe, making wind blown sand the main building choice an urgent need. This study innovatively utilized local waste drilling mud and lignin composite materials to improve aeolian sand, exploring the effects of different ratios of composite solidification materials on the unconfined compressive strength and impermeability characteristics of sand samples. The research results show that: ① Drilling mud and lignin as solidifiers can significantly improve the unconfined compressive strength of sand samples, and its strength shows a linear increasing trend, and with the extension of curing time, it first decreases and then tends to stabilize. ② With the addition of curing agent, the impermeability of the sample has been significantly improved, and this trend shows an initial decrease followed by a stabilization over time. The appropriate proportion of drilling mud and lignin fills the pores inside the sample, wraps around soil particles, and optimizes their structure, making the soil more compact. At the same time, combined with the bonding effect of ion curing agents, it can effectively reduce the size and connectivity of pores, thereby enhancing their ability to resist water infiltration. ③ A composite wind blown sand solidifier was proposed, with an optimal ratio of 3% drilling mud and 8% lignin. This solidifier is economical and environmentally friendly. This study can provide a new idea for the improvement of building materials and the resource utilization of drilling mud in the northwest wind blown sand area.

To enhance the erosion resistance of loess slopes, urease-induced calcium carbonate precipitation (EICP) technology was introduced to strengthen the loess slope in this study. Through permeability, disintegration, slope model erosion, and microscopic tests, the water stability and erosion resistance of EICP-treated loess under different treatment conditions were systematically studied, and its treatment mechanism was discussed. The results indicate that the permeability and anti-disintegration characteristics of loess can be significantly improved after two rounds of EICP treatment when the soybean urease concentration is 80 g/L, the cementation solution concentration is 1.0 mol/L, and the mixture ratio is 1∶1. Under simulated extreme rainfall conditions, no splash erosion pits or gullies developed on the solidified slope. The runoff rate remained stable, sediment concentration in the runoff was negligible, and the water content of the slope increased significantly less than that of an unsolidified slope. Additionally, the difference in elevation between the two types of slopes after erosion follows the normal distribution approximately. Microscopic analysis shows that the cementation solution concentration dominates the effect of EICP treatment by regulating the size and spatial continuity of calcium carbonate crystals. This technology forms a dense three-dimensional network structure within the loess, which effectively divides the pore structure of soils. Therefore, EICP technology has good engineering application potential in improving the impermeability and erosion resistance of loess slopes.

Shallow fine roots enhance soil shear strength and play a critical role in vegetated slope stability. While prior research focused on factors like soil type, moisture, root arrangement, and plant species, the relationship between root characteristics and root-soil composite strength remains underexplored. This study employs direct shear tests on saturated Amorpha fruticosa root-loess composites to systematically investigate the influence of root content, root length, and key parameters (root area index - RAI, root length density - RLD, root volume ratio - R_v) on shear strength. Results show: ①under low vertical loads, shear strength increases significantly with root content, but this effect weakens under higher loads; ② reinforcement primarily enhances cohesion, with minimal impact on internal friction angle; ③ for root length ≥2 cm, an optimal root content (1%-1.5%) maximizes cohesion; ④ shear strength correlates strongly positively with RAI and R_v, but weakly with root content, biomass, RLD, and specific root length, indicating dominance of root-soil interface friction under saturation. This work clarifies the mechanical mechanisms of root reinforcement in saturated loess, identifies a specific optimal root content, defines key root characteristic-strength relationships (RAI, R_v, average diameter), and provides a new theoretical basis for the comprehensive understanding of the mechanical effects of vegetation slope protection in loess areas and the scientific design of ecological slopes.

The railway network in the Loess Plateau routinely traverses high-density farmland irrigation corridors, where the subgrade continuously accumulates excessive post-construction settlement, severely threatening the millimeter-level smoothness control requirements of railways and posing significant challenges to train operation safety. This study addresses the prominent conflict between routine farmland irrigation practices and the stability requirements of railway subgrades in this region. Through field investigations at a typical site along the Baoji-Zhongwei Railway and dynamic triaxial laboratory tests, the causes of subsidence in loess subgrades under irrigation were identified, and the dynamic residual deformation characteristics of loess after wetting were revealed, along with proposed prevention-control thresholds. The research demonstrates that periodic irrigation-induced moisture fluctuations in the subgrade soil, combined with long-term cyclic train loads, are the primary drivers of severe settlement. By conducting comparative simulation tests of train load waveforms under varying drainage conditions, it was found that the residual strain under semi-sinusoidal wave loads decreased by 15%~20% compared to conventional sinusoidal waves, confirming that semi-sinusoidal waves better reflect real-world train dynamic load characteristics. A dynamic residual strain model for loess was established, incorporating consolidation stress, dynamic stress amplitude, and vibration cycles. Preliminary predictions of subsidence in actual irrigation zones using this model aligned well with field observations. The findings provide a theoretical foundation for long-term settlement prediction of railway subgrades in loess regions and hold significant engineering value for advancing lifecycle safety assessments of subgrade defects under coupled vibration-seepage interactions.

The identification and measurement of rock joint cracks is an important basis for the characteristics of rock structural planes and the evaluation of rock quality. The traditional identification of rock joint cracks in boreholes is mainly manual and inefficient. In this paper, the deep learning convolution neural network Mask R-CNN algorithm model is used to construct the data set by labeling and standardizing the features of the image joints and cracks. The Mask R-CNN model is trained to construct the intelligent recognition and segmentation model of rock joints and cracks, so as to realize the intelligent recognition and segmentation of the observed image. The rock joint cracks are skeletonized by binarization and sine wave fitting, and the occurrence of rock joint cracks is calculated, so as to realize the statistics of rock joint cracks on the borehole wall by digital means. The technology is compared and verified by project examples. The results show: ①the non-directional rock joint fracture can be extracted by a specific algorithm model, and its corresponding occurrence can be calculated by multi-point fitting of sine curve. ②The accuracy of the measurement results can reach more than 85 %. ③With the increase of the number of different morphological samples of joint cracks, the recognition accuracy can be increased. ④The intelligent identification and measurement results of rock joint cracks can describe the rock structural plane in detail and be applied to the evaluation of rock integrity and quality grade.

In response to the complex formation mechanism of loess landslide disasters and the insufficient accuracy of traditional investigation methods, this study proposes a "space ground number" collaborative analysis method. The typical loess landslide body that occurred in Yangjiagou Town Industrial Park, Mizhi County on September 14, 2023, is taken as the research object. Three dimensional terrain data with centimeter level resolution is obtained through unmanned aerial vehicle aerial survey technology to reconstruct the geometric shape characteristics of the landslide body; Reveal the characteristics of controlling structural planes and stratigraphic combinations through on-site geological surveys. Based on the mixed finite element discrete element numerical simulation (Y-Mat), a dual scale model considering the real geometric shape and structural plane distribution is constructed. Through simulation, it is revealed that due to the influence of terrain and crack water conduction, the slope foot softens when encountering water, the strength decreases, and the upper loess body is pulled to deform. When the deformation accumulates to a certain extent, it collapses downwards along the original through water conduction cracks. During the falling process, some loess disintegrates and accumulates within a certain range of the slope foot, forming loess blocks and loose soil of different sizes, which impact the buildings at the slope foot and cause them to collapse. The research results can provide multi-source data fusion analysis methods and technical support for the study of the evolution mechanism of landslide geological hazards in the Loess Plateau.

Land surface displacement is the most intuitive feature of the development, evolution and destruction of geological hazards. MT-InSAR technology can achieve long-term monitoring of land surface displacement, but its data processing process is time-consuming and requires specialized knowledge of processing personnel, which seriously hinders its widespread application. Based on this, the author introduces the characteristics of the data of the HyP3 cloud platform, analyzes the difficulties of land surface deformation monitoring based on this data with large phase unwrapping error and inconsistent deformation reference, and designs a technical route for MT-InSAR monitoring of surface deformation based on HyP3 cloud platform. This technical route suppresses the influence of phase unwrapping error on the deformation monitoring results by adding the automatic selection of the unwrapped interferogram and the correction step of the phase unwrapping error in the traditional SBAS-InSAR technology. In this paper, in the phase unwrapping error correction step, the phase non-closing problem is solved by restoring the reference phase, and the problem of no feasible solution in linear programming is solved by adding relaxation variables. The proposed technical route is used to obtain the surface deformation of Yan'an New District in 2020～2021, and the reliability of the technical route is verified by comparing with the calculation results based on the original SAR data.

In the grouting reinforcement of water-rich sand layers, the pore structure and spatial distribution of the cemented bodies directly influence reinforcement effectiveness and grout diffusion paths, serving as critical criteria for evaluating grouting quality and optimizing operational parameters. However, due to variations in sand grain size distribution and non-uniform grout diffusion, existing studies remain insufficient in characterizing multi-scale pore structures, particularly lacking systematic validation of the evolution and interrelation of micro–macro pore structures under different sand grain sizes. This study aims to reveal the evolution patterns and spatial distribution characteristics of pore structures in cemented bodies formed in water-rich sand layers with different grain sizes, providing references for understanding grouting mechanisms and selecting engineering parameters. Under consistent grouting materials and injection pressure, simulated grouting tests were conducted on fine, medium, and coarse water-rich sand layers to prepare typical cemented body samples. Micro-scale pore structures were quantitatively analyzed using mercury intrusion porosimetry, while macro-scale pore characteristics were extracted and binarized using MATLAB digital image analysis to calculate porosity. By integrating micro-scale and macro-scale data, a multi-scale pore structure analysis framework was established to systematically compare differences and spatial patterns in the pore structures of cemented bodies across different grain sizes. At the micro-scale, fine cemented bodies are dominated by slit-like and irregular medium-to-large pores, exhibiting high connectivity and the highest porosity; medium cemented bodies show a composite structure of slit-like and spherical pores, with a wide pore size distribution and the most complex structure; coarse cemented bodies mainly develop long columnar or small-to-medium spherical pores, with the lowest porosity, indicating that coarse-grained skeletons favor densification. At the macro-scale, porosity of all three cemented body types increases parabolically with distance from the grout outlet, reaching the minimum at X = 0 cm, with fitting coefficients R² ranging from 0.70 to 0.92, reflecting the spatial characteristics of saturated grout deposition. Micro-scale porosimetry and macro-scale image analysis results were highly consistent, all showing a porosity ranking of “fine > medium > coarse,” validating the reliability of the image analysis method. The study reveals the multi-scale pore structure characteristics and spatial distribution patterns of cemented bodies in water-rich sand layers under different grain size conditions, clarifying the control of grain size on pore morphology, porosity, and densification. The findings provide a scientific basis for understanding grout diffusion and deposition mechanisms, optimizing grouting materials and parameters, and improving reinforcement quality, offering significant engineering applications.

Tongwan City, which is located in Jingbian, Yulin, Shaanxi Province, is the only Xiongnu city site in China, carrying rich historical culture and scientific value. Despite over 1,600 years of weathering and freeze-thaw cycles, the heritage site has been preserved to this day. Therefore, it is important to study the material composition, mechanical properties and microstructure of the site soil for the restoration of heritage site. Taking the site soil at Tongwan City as the research object, this study conducted laboratory tests on physical and mechanical properties, X-ray diffraction(XRD), X-ray fluorescence(XRF) spectroscopy, scanning electron microscope (SEM) and computed tomography (CT) scanning to analyze the macro and micro characteristics of the site soil. Based on the above research, some conclusions are as follows. ① The primary mineral components of the site soil include quartz, feldspar, calcite and dolomite, and its calcium ion content is significantly higher than the surrounding soil samples, this indicates that lime material was intentionally added during the construction of Tongwan City. ② Compared with undisturbed loess in the surrounding area, the site soil has higher shear strength and low compressibility, the shear curve exhibits distinct brittle failure deformation characteristics, and the compression coefficient is smaller. ③ Microstructural analysis reveal that face-to-face contacts dominate the particle interactions in the site soil. Calcium carbonate cement interweaves densely among particles, adhering to particle surfaces and bridging interparticle spaces, which reduces the proportion of macropores, enhances particle interconnections, and increases the overall density of the soil structure.

Bailong River Basin is one of the most developed and serious areas of debris flow disaster chain in China. In order to support and serve the disaster prevention and mitigation of the large geological chain in Bailong River Basin, the debris flow in Zhaizigou, Zhouqu County, Gansu Province, was selected as the research object. Through on-site survey and mapping, combined with multi-period remote sensing data, laboratory test and numerical simulation results, the development characteristics, formation conditions and evolution model of debris flow were discussed in depth. Finally, the paper puts forward some suggestions on preventing the risk of debris flow disaster chain.The results show that: Zhaizigou is a gully type debris flow, the longitudinal slope of the gully bed is 324.5‰, and the high level source amount is 2129.23×10⁴ m³. The key disaster landform of Zhaizigou is unique, the necessary disaster formation and disaster control structure are complex, and the important triggering conditions are obvious, which has all the conditions for the occurrence of a huge debris flow disaster chain. The evolution model of the disaster chain is the disaster chain of high level collapse-barrier body collapse-debris flow, barrier lake and outburst flood. On this basis, it is proposed that the risk prevention and control of the disaster chain of the huge mudflow in Bailong River basin should focus on strengthening the disaster chain investigation and identification ability, tackling the key disaster chain monitoring, early warning, forecasting and risk prevention and control technology, and strengthening the disaster chain project disaster prevention and reduction and emergency disposal capacity. Finally, according to the characteristics and key problems of different risk areas from the perspective of river basin, the risk prevention and control model of Zhaizigou debris flow disaster chain risk prevention and control is constructed, which can provide reference for the disaster prevention and reduction of similar massive debris flow disaster chain in western mountainous areas.

This study aims to unravel the genetic mechanism governing the high-angle sharp bends of the Yellow River channel that cut across mountain ranges within the Lanzhou–Zhongwei Shapotou reach on the northeastern margin of the Tibetan Plateau, as well as to clarify the controlling effects of fault structures on the formation and long-term evolution of the river channel. Integrating field geological surveys, remote sensing interpretation, and regional geological analysis with tectonic geomorphology, this study focused on the geological structural characteristics of the two representative high-angle bend segments at Luoquanwan in Lanzhou and Wufo Township in Jingtai. The distribution and activity properties of fault systems were analyzed to evaluate their impacts on the spatial alignment of the Yellow River channel. Our results demonstrate that the Lanzhou–Zhongwei reach of the Yellow River is predominantly aligned along NE-, NEE-, and NW-trending fault zones, with particularly strong control exerted by NE-trending extensional strike-slip faults. These faults represent the key structural driver that facilitated river incision through mountain ranges and triggered channel avulsions. At both Luoquanwan and Wufo Township, the river did not follow the pre-existing NW–SE trending piedmont depression zones for natural downstream propagation, instead, it developed near right-angle sharp bends and cut across or obliquely traversed the NW-SE trending mountain ranges. The Yellow River channel predominantly develops within tectonic junctions and structural fracture zones formed by regional faults. The intersection, strike-slip, and thrusting of NE-trending and NW–NWW-trending faults collectively contribute to the short-line, high-angle bends of the river channel and its traversal of topographically elevated mountain systems. The Yellow River channel is primarily developed within tectonic junctions and structural fracture or fault crush zones formed by regional fault systems. Fault structures are the dominant controlling factor governing the channel extension and bending, particularly in driving the river to deviate from its original main course direction, dissect mountains, and traverse or obliquely cut across mountain systems via short-line, high-angle bends.

The ocean-continent pattern, sedimentary tectonic evolution and the relationship between adjacent blocks in the Qin-Qi-He crosslinking area on the southwest margin of the North China Craton since the Early Paleozoic have been the focus of research in recent years. In this paper, LA-ICP-MS zircon U-Pb geochronological analysis is used to analyze a set of coarse clastic molarite sedimentary rocks, which were previously thought to belong to Silurian and Devonian but lack of fossil records, from Xianghuanggou section in Nanhuashan area, northeastern margin of the North Qilian tectonic belt. Clastic rock samples were collected and detrital zircon U-Pb dating analysis was performed. The results show that the U-Pb concordant age of the youngest zircon is 230.2±2.6 Ma, and the concordant age of several younger zircons is 232±5 Ma, 232±3 Ma and 236.7±2.4 Ma, respectively. U-Pb weighted age of the youngest zircon is 233.2±5.1 Ma, and the earliest depositional age of the host strata is the Late Triassic. Combined with the age spectrum of detrital zircons from the adjacent stratigraphic units, it is concluded that the main body of the molarite sedimentary strata in the study area belongs to the Upper Triassic sedimentary stratigraphic units. It does not support the traditional understanding of the Silurian Devonian system in the past. According to the comparative analysis of regional age spectrum, the Late Triassic coarse clastic molarite sedimentary rocks in Xianghuanggou section of Nanhuashan Mountain are mainly derived from the North Qinling and Alxa areas in the Early Mesozoic, and the Qilian-North Qinling areas in the Early Paleozoic. The source of Precambrian detrital material is a bidirectional mixture source between the North China plate and the Qilian-North Qinling orogenic belt. The conglomerate deposits were mainly controlled by the tectonism of the Qin-Qi collisional orogenic belt in the Indosinian period, and should belong to the sedimentary tectonic response of the final collisional closure process of the Qin-Qi trough in the Indosinian period.

The Carboniferous strata in the northwestern margin of the Junggar Basin represent an important target for deep hydrocarbon exploration, with the characteristics and formation background of source rocks attracting significant attention. This study focuses on the dark mudstones of the Carboniferous strata in Well MH55, utilizing systematic sampling and organic-inorganic geochemical analyses to investigate their hydrocarbon potential, paleo-depositional environment, and organic matter enrichment mechanisms. The results reveal that the organic matter content in the dark mudstones of Well MH55 is moderate, dominated by Type Ⅲ kerogen. The source rocks exhibit a high degree of thermal maturity with significant fluctuations, likely influenced by frictional heating associated with fault activity, and are overall classified as poor-to-moderate source rocks. The mudstones were deposited in a brackish-to-saline transitional environment characterized by dysoxic water conditions and oscillating climatic shifts between warm-humid and cold-arid periods. Organic matter enrichment was primarily controlled by terrigenous input and dysoxic conditions. Terrigenous input provided the primary source of organic matter, while dysoxic conditions effectively reduced organic matter oxidation and decomposition rates. In contrast, the contribution of paleo-productivity was relatively limited, which may be attributed to insufficient nutrient availability in the water column and dilution effects from terrigenous material input during deposition.

The Mayidang, Tu'erkuli, Keyinnan and other graphite deposits in the Moqinwula area of the East Junggar Basin, Xinjiang, are newly discovered deposits with industrial value in recent years. Taking the Tu'erkuli graphite Deposit as the research object, this study carried out LA-ICP-MS zircon U-Pb dating and petrogeochemical analysis. Chronological results show that the ore-hosting stratum of this deposit formed at 334±9 Ma, and the graphite mineralization occurred at 313 Ma. The petrogeochemical characteristics are as follows: the graphite ore is enriched in lithophile elements such as Rb, Ba, Pb and Sr, and depleted in high field strength elements (HFSEs) including Th, Nb, Ta and Ti; the total content of rare earth elements (REEs) is relatively low, with ΣREE ranging from 52.16×10⁻⁶ to 134.21×10⁻⁶ and an average of 81.71×10⁻⁶. These features indicate that the sedimentary materials of the ore-bearing rocks were derived from terrigenous clastic rocks, and the rocks formed in a neritic-epicontinental anoxic reducing sedimentary environment. Comprehensive research suggests that the ore-hosting stratum of graphite deposits in the Moqinwula area of East Junggar is the Lower Carboniferous Jiangbasitao Formation, which corrects the previous understanding that it belonged to the Upper Silurian-Lower Devonian Hongliugou Formation. This deposit is a contact metamorphic graphite deposit. Its genetic mechanism is as follows: under the superimposed transformation of late tectonic activities and magmatic intrusion, the organic matter in the carbon-bearing sedimentary rock series of the Lower Carboniferous Jiangbasitao Formation was activated, undergoing deoxidation and dehydrogenation reactions followed by recrystallization, and finally forming crystalline graphite.

The Xinjie Taigemiao mining area of Dongsheng Coalfield contains rich coal resources, which is located in the Ejin Horo Banner and Wushen Banner, Ordos City, Inner Mongolia Autonomous Region. However, the coal quality has not been comprehensively evaluated at present, which seriously restricts the clean and efficient utilization of coal resources in the future. Based on the abundant geological exploration data, we comprehensively analyzes the coal quality and coal rock characteristics of the Yan'an Formation coal in the Xinjie Taigemiao mining area. Combined with the classification of coal cleanliness levels and the evaluation index system of various coal clean utilization directions, the clean potential and clean utilization direction of the Yan'an Formation coal in the Taigemiao mining area are comprehensively evaluated. The results show that the Yan'an Formation coal in the Taigemiao mining area has the characteristics of ultra-low ash, ultra-low low sulfur, low harmful elements, and high calorific value. These characteristics indicate that the Yan'an Formation coal is high-quality, high cleanliness power coal, and is comprehensively evaluated as Class II power coal. The characteristics of high tar yield (generally＞7%), medium high volatile matter, high fixed carbon, ultra-low ash content, and low moisture content indicate that it is suitable for low-temperature pyrolysis extraction of coal tar (Class I). In addition, its cohesiveness, low moisture content, high hydrogen to carbon atomic ratio, and high inertinite contents, indicate that it is also suitable for liquefaction coal. Based on the development planning goals of the mining area, we proposed that the Yan'an Formation coal in the Taigemiao mining area has a high potential for clean energy, and the advantageous utilization directions are clean power coal and coal for tar production.

The Gufang-Yangying area in the southeast of Fengning Manchu Autonomous County, Hebei Province, is located at the northern margin of the North China Craton, tectonically situated at the junction between the northern margin uplift belt of the North China Craton and the Chengde North Basin of the Yanshan-Liaoxi rift zone, adjacent to the Shangyi-Longhua regional fault. The area is dominated by metamorphic rock series of the Neoarchean Upper Chongli Group (Yangying and Aijiagou formations), with complex structures, well-developed folds, and iron deposits primarily consisting of sedimentary-metamorphic iron ore and ultra-poor magnetite, generally positioned along northeast-trending tight synclinal structures. Although previous geophysical surveys have been conducted, large-scale high-precision ground magnetic measurements remain insufficient, resulting in inadequate delineation of three-dimensional deep ore body structures and constraining deep prospecting efforts. This study, based on 1∶5000 high-precision ground magnetic survey data, employs reduction to pole, variable-height upward continuation, field separation, analytical signal, vertical derivative, and tilt derivative processing, combined with rock physical property statistics, and utilizes the open-source SimPEG framework for three-dimensional magnetic susceptibility inversion to reveal the spatial distribution characteristics of magnetic bodies within a 1 km depth range; rock physical properties indicate significant magnetic contrast between mineralized iron-bearing rocks and host rocks, providing a robust foundation for magnetic exploration. Inversion results show that magnetic bodies are distributed in a northeast-southwest trending strip-like pattern, mainly concentrated in the central-eastern and southwestern parts, highly consistent with known surface ore bodies and the Upper Chongli Group metamorphic series; vertically, they exhibit scattered distribution in shallow depths, concentrated and continuous in middle depths, and rapid weakening in deeper levels, with three-dimensional displays at different susceptibility thresholds further confirming that high-susceptibility zones are predominantly in the central-eastern part, forming large lens-shaped bodies that partially extend close to the surface, reflecting progressive thickening and enlargement of ore bodies along dip directions. The study confirms that sedimentary-metamorphic iron deposits in the area are controlled by Neoarchean regional metamorphism, conforming to the typical BIF-type metallogenic model at the northern margin of the North China Craton; high-precision three-dimensional susceptibility inversion effectively addresses the knowledge gap in deep structures under complex geological conditions, providing high-resolution geophysical evidence for precise localization of concealed ore bodies, with the central-eastern high-susceptibility zone representing the most favorable target for deep prospecting and warranting priority for drilling verification. These findings deepen understanding of deep metallogenic elements in the study area and offer reliable technical approaches and integrated geological-geophysical methodologies for deep prediction in similar sedimentary-metamorphic iron ore districts along the northern margin of the North China Craton.

Ecology-supporting sphere is an important part of natural resources, and it is the basic material that supports and nurtures various natural resources and ecological environment. Taking Ningxiang City as an example, this paper constructs a cultivated land suitability evaluation system with 10 evaluation indexes from the surface form, physical and chemical properties, and internal structure, and analyzes the existing cultivated land resources on the basis of serving the construction of ecological civilization. The results showed that: ① In general, Ningxiang City had a high suitability level of cultivated land, and the suitable area was about 1 164.67 km² accounting for 40.08%. The suitability level showed a distribution trend of high in the east and low in the west. ② Superimposing the land use status, it is found that the cultivated land of suitable grade is concentrated in the northeast and parts of southeast.The more suitable cultivated land is mainly distributed in the southwest towns. The less suitable and unsuitable cultivated land is mainly concentrated in the central and south-southeast regions. High-quality reserve cultivated land resources are mainly distributed in the towns with relatively flat terrain in the east. ③ Through exploring the factors that affect the utilization of cultivated land, the suitable cultivated land conservation measures should be strengthened to ensure the stable yield of high-yield fields.The more suitable cultivated land needs to carry out slope farmland management and improve soil ph. And the less suitable and unsuitable cultivated land should strengthen mine restoration, water and fertilizer conservation and acid regulation. In order to promote the sustainable development of land, the emphasis of reserve cultivated land development should be placed on the towns in the northeast, and the towns in the southeast and southwest should strengthen the protection of ecological environment. These results can provide the basis for the next cultivated land regulation and development in Ningxiang city.

Evaporation-induced salt precipitation in the soil-groundwater system is widespread in arid regions. However, there is no consensus on whether the temporal stage division of evaporation for saline water is consistent with that for pure water, which limits a deeper understanding of evaporation-induced salt precipitation in soil-groundwater system. To clarify the stage division and the controlling factors of evaporation-induced salt precipitation under different NaCl concentrations, indoor soil-column experiments were conducted using quartz sand as the porous medium. Five concentrations were tested: 0, 1, 3, 10, and 50 g/L NaCl. Two parallel replicates were performed for each concentration, giving a total of ten soil columns. The experiment lasted 43 days. Evaporation was recorded, air temperature, surface temperature and profile temperature were monitored, surface salt precipitation was documented, and the mass of the surface salt crust was measured. The results show that: ① The evaporation of pure water is consistent with previous studies and can be divided into three stages: Stage I, constant-rate or high-rate evaporation (days 1-18); Stage II, transitional or falling-rate evaporation (days 18-37); and Stage III, diffusion-limited or low-rate evaporation (days 37-43). ② Evaporation of saline water can also be divided into three stages, but the onset time and intensity of each stage vary with NaCl concentration. With increasing concentration, Stage I becomes shorter and Stage III starts earlier. For 1, 3, 10, and 50 g/L, Stage I lasted 17, 13, 7 and 4 days, respectively, and Stage III started on days 36, 31, 23 and 17, respectively. For moderate to high saline water (≥10 g/L), earlier development of a surface salt crust led to an earlier transition to Stage III and reduced cumulative evaporation. Using the mean cumulative evaporation of the two replicates, the values for 0, 1, 3, 10, and 50 g/L were 228.25, 131.92, 117.45, 109.53, and 29.16 cm, respectively. ③ The controlling factors vary with both concentration and evaporation stage: temperature potential dominated the early-stage evaporation for pure water, freshwater (1 g/L) and mildly saline water (3 g/L); during the transitional stage for moderately saline water (10 g/L), temperature potential and matric potential were both important, while solute potential became stronger and began to contribute to evaporation suppression; for highly saline water (50 g/L), solute potential dominated in the later stage.

The geological storage of CO₂ in deep saline aquifers of sedimentary basins is the main way of CO₂ storage and an important means to achieve carbon reduction goals on a large scale in the short term. The Qingjiang Basin has developed high quality deep saline reservoirs and cap rocks, which have the potential for CO₂ geological storage. However, there has been no systematic study on its storage geological conditions and potential in the past. By the date collection, field investigation, and testing analysis works, a comprehensive study was conducted on the geological conditions of CO₂ storage in the Qingjiang Basin. Embedded analysis was carried out on the characteristics of reservoir-cap conditions, fault development, hydrogeology, geothermal geology, etc. Using the storage potential calculation formula recommended by the Carbon Storage Leaders Forum, the CO₂ geological storage capacity in the Qingjiang Basin was evaluated. The results show that there are two sets of reservoir-cap combinations suitable for CO₂ storage developed in the deep part of the Qingjiang Basin: in Cretaceous, the glutenite of Hekou Formation is the reservoir, and the argillaceous rocks of Tangbian Formation is the cap rock; the glutenite of Lianhe Formation in Cretaceous and the first member of the Xinyu Formation in Paleogene is the reservoir, and the gypsum and argillaceous rocks of the second, third, fourth member of the Xinyu Formation is the cap rock. Well rock character and mineral composition conditions has been developed in the reservoir, with high porosity and permeability; the advantages in the cap rock has been developed with dense lithology, low porosity and permeability, and high breakthrough pressure. The main control fault of the basin has little impact on the strata deformation of the basin after its formation, and the development scale and fault displacement of secondary faults are not significant. The saline aquifers has hydraulic sealing effect and has no hydraulic connection with surface water sources. After preliminary assessment, the effective CO₂ storage capacity of the deep saline reservoir in the Qingjiang Basin is 3.93×10⁸ t, which is of large storage potential, and can be used as a geological disposal space for CO₂ in the Poyang Lake Economic Circle in northern Jiangxi.