To address the challenge of achieving a balance among mechanical strength, vegetation performance, and anti-scouring capacity in traditional eco-revetment engineering, this study introduces a novel high-porosity vegetated concrete that incorporates dredged silt for effective resource management. For the first time, dredged silt has been employed as an alkali-reducing substrate within the mix design, which was developed by optimizing the gradation of coarse aggregates to mitigate soil erosion and ecological degradation along riverbanks. Extensive investigations were conducted to evaluate the effects of coarse aggregate size, water-to-cement ratio, and mineral admixtures on porosity, compressive strength, and permeability. In addition, comparative alkali-reduction experiments, combined with XRD, XRF, and SEM analyses, were conducted to clarify the respective roles of dredged silt and FeSO4 and to further reveal the microstructural mechanisms of the substrate–concrete system. Furthermore, the alkaline environment was regulated using the optimally proportioned dredged silt mix to perform planting experiments, and its anti-scouring performance was subsequently assessed. The results indicated that under optimal conditions with a coarse aggregate size between 25 and 30 mm, the 28 day compressive strength reached 6.23 MPa, with a porosity of 33
Controlling and predicting frost heave and subsequent thaw settlement are critical challenges in applying artificial ground freezing (AGF) to soft-soil underground engineering. When the soil between adjacent freeze pipes is hydraulically isolated, it behaves as a closed system with limited external water supply. This study investigates the hydrothermal behavior and microstructural evolution of undisturbed soft clay subjected to one-dimensional closed-system freeze-thaw. Freeze-thaw experiments were carried out at different cold-end temperatures, and the resulting pore-structure changes were characterized using mercury intrusion porosimetry (MIP) and fractal analysis. The evolution of the temperature field, freezing-front progression, and vertical displacement was monitored and related to changes in pore structure. The results show that slower freezing, associated with a smaller imposed temperature gradient, allows more internal water to migrate toward the freezing front and results in larger frost-heave strain. At the same time, the resulting closed-system moisture redistribution produces a clear depth-dependent contrast in post-thaw microstructural response. MIP reveals systematic pore-size redistribution and changes in mercury-accessible pore volume and pore-volume distribution heterogeneity after freeze-thaw. Final thaw settlement exceeds maximum frost heave, indicating net bulk shrinkage over the freeze-thaw cycle. Updated mass-balance analysis indicates that this bulk shrinkage was dominated by freeze-thaw-induced structural rearrangement under nominally closed conditions, rather than by appreciable external water loss during thawing. This interpretation is consistent with the post-thaw increase in mercury-accessible pore space, because MIP reflects pore accessibility and connectivity within the soil skeleton rather than specimen-scale volume alone. These findings clarify how thermal boundary conditions regulate internal hydrothermal redistribution and pore-fabric evolution under closed-system freezing and provide an experimental basis for interpreting freeze-thaw deformation in water-limited AGF conditions.
Aiming at the ambiguous hydraulic connectivity of water-rich strata and the technical challenges of water inrush control during deep tunnel construction, this study integrates field tests and theoretical modeling to investigate the hydraulic conduction characteristics of bedrock, the permeability properties of surrounding rock, and the associated grouting mechanisms and prevention technologies. The main findings are as follows. A wireless monitoring system for deep borehole hydraulic connectivity was established to characterize hydraulic conduction behavior at varying depths. Monitoring results reveal favorable hydraulic connectivity between shallow and deep strata, with a water head difference of only 0.3 m. A segmented pressure gauge installation scheme for single boreholes was proposed to eliminate leakage-related defects inherent in conventional testing methods. Field measurements indicate that the maximum permeability of the surrounding rock is 5.30×10−7 m/s, corresponding to weak permeability. Seepage pressure increases with borehole depth, reaching a peak value of 0.24 MPa at a depth of 5.5 m. Based on the Bingham fluid diffusion model, a nonlinear relationship was identified between the rock mass permeability coefficient and grouting diffusion radius, whereas grouting pressure exhibits an approximately linear correlation with slurry diffusion range under fixed geological conditions. Considering in-situ stress and rock strength, the critical grouting pressure for rock failure was determined, and the maximum allowable grouting pressure was set at 8.0 MPa. In line with the proactive disaster prevention philosophy for tunnel engineering, a surface advanced directional drilling and grouting technique was proposed and validated using hydraulic connectivity data. Four grouting holes were arranged within a 7 m radius and 2.5 m from the tunnel contour. The water head at the monitoring point located 70 m from the tunnel axis increased by 4
As one of the serious issues facing the world currently, precipitation changes are causing substantial shifts in earth’s biotic systems. Precipitation affects plant growth processes at multiple ecological scales, including population, community and ecosystem level. However, the absence of reconciliation across different scales means that the impact of precipitation changes on plant growth continues to be a significant source of uncertainty in future climate projections. We explored the effects of precipitation change on grassland plant growth at population, community, and ecosystem level, by conducting a meta-analysis of 3625 observations from 168 studies worldwide. Our findings reveal that the effects of precipitation change on grassland plant growth differ significantly across various scales, and they are gradually weakening, from population (e.g., photosynthesis: d = 1.674, p < 0.001), community (e.g., carbon content: d = 1.598, p < 0.001), to ecosystem level (e.g., plant abundance: d = −1.267, p < 0.001). Further, at both the population and community levels, plant growth showed greater sensitivity to increases in precipitation (e.g., photosynthesis: population, d = 1.674, p < 0.001; community, d = 0.717, p = 0.001) compared to decreases (e.g., photosynthesis: population, d = −0.532, p < 0.001; community, d = −0.474, p = 0.45), and more sensitive to decreased precipitation at ecosystem level (e.g., plant abundance: increased, d = 0.152, p = 0.601; decreased, d = −1.267, p < 0.001). Our synthesis highlights that accurately quantifying the varying responses of plant growth necessitates explicit attention to organizational levels and the magnitude of experimental manipulation. Our finding has important implications for reliably modelling terrestrial carbon and water cycles, thus accurately predicting the impact of future climate change.
Flood simulation and forecasting are fundamental to effective watershed management, particularly under the combined influences of climate change and intensified human activities. Conventional calibration strategies for hydrological models often struggle to maintain stable performance across floods of different magnitudes due to scale dependent differences in runoff generation and routing processes. To address this limitation, this study proposes a hierarchical calibration framework that explicitly links model parameter estimation to flood magnitude using segmented net rainfall thresholds. Based on observed flood events in the Yuecheng Catchment, thresholds of 25 mm, 13.5 mm, and 12.5 mm were identified for small, medium, and large floods, respectively. DE, SA, and WOA were employed to calibrate the parameters of the Xin’anjiang model within this hierarchical framework, and their impacts on flood simulation performance were systematically evaluated. The results demonstrate that the proposed hierarchical calibration framework substantially improves model adaptability and simulation accuracy across different flood magnitudes. Mean NSE values generally exceeded 0.94, while mean MARE remained below 15
Rock bolts are widely adopted in slope stabilization and underground construction due to their cost-effectiveness and capacity to satisfy demanding requirements for load-bearing and deformation control. Nevertheless, a comprehensive understanding of their mechanical behavior under varying encapsulation lengths and grout compositions remains lacking, primarily owing to the scarcity of systematic experimental investigations and precise internal measurements. To address this gap, this study conducts large-scale pull-out tests following a full factorial experimental design, integrating both external load and internal strain measurements to systematically evaluate the effects of encapsulation length and grout properties on bolt performance. The results indicate that both factors significantly influence the load-bearing response under pull-out conditions. Specifically, longer bolts and high-strength, low-stiffness grouts exhibited greater overall stiffness, thereby enhancing resistance to deformation. Increasing encapsulation length improved ultimate load capacity, reduced unit displacement per unit length, and alleviated stress concentration along the bolt shaft. The influence of grout type was primarily governed by its compressive strength, with softer, lower-strength grouts promoting more uniform internal force distributions along the bolt. Although no significant interaction effect was observed between the two factors, their individual contributions were distinct: encapsulation length exerted a stronger influence on ultimate load capacity, whereas grout type predominantly affected ultimate displacement and shear strength.
Rockburst is a critical dynamic hazard in deep high-stress hard rock tunnels. The Daxiagu Tunnel in southwestern China, crossing extensive horizontally layered dolomite under ultra-high stress, suffers frequent rockbursts poorly predicted by traditional methods, as most existing energy criteria are derived from intact rock without bedding weakening correction. This study develops a modified rockburst energy criterion via triaxial unloading tests, numerical simulation and field validation. Under 40 MPa confining pressure, dolomite energy storage limits drop to 52
There is no consensus on the appropriate number of subwatersheds to delineate in a basin, nor a widely accepted methodology for identifying optimal delineation thresholds. Past studies indicated that neither very fine subwatershed discretization nor overly simplified representations consistently perform better in hydrological and nutrient modeling. Consequently, the development of an efficient and objective methodology to reduce the labor-intensive trial-and-error process of determining optimal subwatershed thresholds remains a challenge. This study applies a variance-based segmentation technique to the sequences of subwatersheds delineated using variable drainage area thresholds. The method is validated using hydrological simulation in the Soil and Water Assessment Tool (SWAT). The approach is evaluated across 18 mountainous sub-basins on the southern slope of the central Himalaya to identify statistically optimal upstream contributing area (UCA) thresholds. At the regional scale, an optimal UCA threshold of 45 km2 was identified, while sub-basin-specific thresholds ranged from 39 km2 to 51 km2. SWAT simulations at the case study basin support the statistically identified threshold, yielding Nash-Sutcliffe Efficiency (NSE) of 0.72 to 0.81, coefficient of determination (R2) of 0.74 to 0.82, and satisfactory error metrics. The identified thresholds exhibit a power-law relationship with basin size when normalized by basin area, indicating that drainage area thresholds are scale-dependent rather than fixed values. Larger basins were associated with smaller threshold-to-basin-area fractions, whereas smaller basins exhibited higher fractions. Across the study region, the optimal threshold consistently corresponded to less than 5
Predicting spatial changes in plant species distribution under climate change remains a critical challenge in biogeography and ecology. The genus Quercus L. is notable for its high ecological diversity and substantial economic value, particularly for hardwood production. However, the natural distribution of oak species is severely threatened by anthropogenic activities, including overgrazing, urbanization, agriculture, and deforestation, which have led to widespread forest fragmentation. In this study, we employed the HadGEM3-GC31-LL global climate model and two Shared Socio-economic Pathway (SSP) scenarios to assess the current and future potential distribution of the Mediterranean species Quercus coccifera L. and its suitable habitats in North Africa. Predictive modeling was conducted using an ensemble approach integrating three Species Distribution Models (SDMs), Boosted Regression Trees (BRT), Generalized Linear Models (GLM), and Random Forests (RF), implemented in R version 1.1–8. Our findings indicate that under all evaluated climate scenarios for the 2050s and 2070s, habitat suitability and distribution range of Q. coccifera in North Africa will decline. Under both SSP scenarios, only marginal expansions (0.02
The Rock Glacier Inventories and Kinematics (RGIK) guidelines provide a standardized methodological framework with technical definitions and criteria for compiling consistent rock glacier inventories. However, the level of consistency attainable under these guidelines remains unclear, particularly regarding which components of the RGIK protocol pose the greatest challenges to novice operators (e.g., students or stakeholders) and how the associated learning curve unfolds. In this contribution, we evaluate inventories compiled in Val Grisenche (Western European Alps) by two graduate fellows (Op2 and Op3) against a reference benchmark produced by an expert scientist (Op1). The two novice operators differed in academic background but shared two months of identical RGIK training. Methods included traditional rock glacier detection and mapping on optical imagery and LiDAR-derived hillshade, complemented by kinematic characterization of rock glacier activity using Sentinel-1 InSAR-derived information. Results indicate that the detection of rock glacier units on optical imagery, as well as the identification of slow-moving areas (1–3 cm yr−1 and 3–10 cm yr−1) on long-duration (typically noisier) interferograms, represent the most critical methodological components requiring additional training. Manual detection of rock glacier units achieved a success rate of 60
On the summit and along the cliff faces of Shiba Luohan Mountain Park in Guangzhou, a diverse suite of sandstone landforms is documented. The existing interpretations—reflected in both scholarly literature and the park’s official interpretive signage—attribute these features to marine processes, specifically the remnants of submarine lava flows and wave-erosion pits at 127.3 m above present sea level, and ancient wave-cut platforms at 87 m along the cliff faces. However, these interpretations are inconsistent with regional geological and geomorphological constraints and no diagnostic evidence supports their marine origin. The central scientific question thus arises: Are these landforms of marine origin, or do they represent products of in-situ sandstone weathering and erosion? To address this, we conduct a systematic investigation into the formation processes of these landforms and the Cenozoic–Quaternary geological evolution of the broader region encompassing the park. Integrating field geological mapping, geochemical element analysis, quantitative mineralogical characterization, and rock mechanical property testing, this study demonstrates that the observed landforms were predominantly formed through subaerial sandstone weathering and surface runoff–driven erosion, rather than marine or coastal processes. These findings fundamentally revise prevailing geological interpretations and the park’s official interpretive narratives, highlighting the imperative for evidence-based geoscience communication in geoheritage management.
The frequent instability of mud-sand interbedded slopes near the Three Gorges Reservoir area in China has drawn significant attention. Under the combined effects of valley down-cutting and rainfall, understanding the failure mechanisms and enabling rapid stability assessments of gently inclined mud-sand interbedded slopes are critical for engineering practice. This study takes the Pengjiawan ancient landslide in the Zigui Basin as an example. An integrated approach including geological surveys, borehole exploration, and numerical simulations is adopted to analyze the geological evolution and failure mechanisms of such slopes. Based on field investigations, an improved transfer coefficient method is proposed that incorporates valley downcutting and rainfall. The influence of key factors on slope stability is systematically examined through orthogonal testing. The results indicate that slope failure initiates within the mudstone layer. The fresh mudstone in the middle of the slope, together with the overlying load-bearing rock layer, forms a T-shaped locking section that governs slope stability. Under valley downcutting and rainfall, the water-filling height at the trailing edge of the slope and the exposure depth of the mudstone layer at the leading edge are the primary triggers of sudden slope collapse. Variance analysis further reveals that slope angles, internal friction angle of mudstone, water-filling height ratio of trailing-edge tensile cracks, and valley down-cutting angle all significantly influence slope stability. These findings offer valuable engineering insights for the prevention and control of landslide disasters on gently inclined mud-sand interbedded slopes.
Forest fires in tropical regions are increasingly influenced by climate change, posing serious threats to biodiversity, livelihoods, and ecosystem stability. This study applies the Maximum Entropy (MaxEnt) model to predict forest fire occurrence in northern Vietnam under current and future climate scenarios (Representative Concentration Pathways (RCP) 4.5 and RCP 8.5 for 2050 and 2070). Using nine environmental predictors and 20 years of active fire data from Fire Information for Resource Management System (FIRMS), we identified temperature seasonality, elevation, and slope as key drivers of fire risk. The model achieved a mean Area Under the Curve (AUC) of 0.71, with temperature seasonality contributing 54.1
Small watersheds in low mountainous areas play a critical role in downstream river dynamics by serving as key sources of sediment transport. Moreover, these regions are prone to sudden and intense flash floods, particularly during extreme weather events, which have profoundly reshaped the morphology of small streams in the Mecsek Hills and surrounding rural areas over the past two decades. Despite their significance, prior research on the hydromorphological characteristics of headwater catchments in low mountainous regions of Hungary remains scarce. This study aims to investigate the essential hydrogeomorphological properties of a first-order stream catchment, with the goal of assessing flash flood vulnerability and the complex interactions among landforms within a micro-watershed. To this end, an extensive and detailed Geographic Information System (GIS) analysis was conducted at 50-meter segment intervals. Results indicate that, relative to the broader Mecsek Hills region, the study area exhibits moderate to medium susceptibility to flash floods. Field assessments further revealed that 72 out of 103 surveyed stream segments contained stable woody debris jams—important channel features that function as natural barriers, influence channel evolution, and contribute to flood hazard mitigation. These findings enhance the understanding of headwater catchment dynamics and provide a basis for improving flood risk management in similar low-mountain landscapes.
The subgrade–tunnel transition section (STTS) is critical to railway lines and is prone to differential settlement and longitudinal temperature gradients, threatening operational safety. Existing studies have mostly examined the mechanical responses caused by differential settlement or temperature loading separately, while their coupled effects on concrete damage and interlayer bonding degradation in ballastless tracks remain insufficiently clarified. To investigate these coupled effects, a finite element model of CRTS I double-block ballastless track in the STTS was established, incorporating concrete damaged plasticity and interlayer bonding. The deformation, damage distribution, and interlayer contact state under coupled loading were analyzed. Results show that increasing longitudinal temperature gradients weaken the bond between the track slab and backfill layer, with damage initiating at slab edges and propagating inward. A settlement wavelength of 5 m minimizes rail upward arch deformation because the track slab ends straddle the settlement trough. Shorter wavelengths and larger amplitudes are more likely to induce interlayer gaps and structural damage. At a wavelength of 5 m, a settlement amplitude of only 15 mm can cause transverse penetrating cracks on the lower surface of the supporting layer. These findings support the safety assessment and maintenance of ballastless tracks in STTSs.
Groundwater investigation requires a structural framework that delineates tectonic features influencing aquifer geometry and characteristics. This study aims to model the subsurface geology of the Badrouna-Sidi Ismail intramontane plain through the integrated analysis of gravity data and vertical electrical soundings. The gravity analysis employs a suite of complementary processing techniques. Upward continuation is applied to separate residual from regional anomalies, while first and second vertical derivatives are used to enhance shallow anomalies and delineate their edges. To refine structural interpretation, additional methods—including total horizontal derivative, analytical signal, tilt angle, theta angle, normalized tilt angle, horizontal gradient tilt, and directional derivatives—are utilized to trace tectonic boundaries. Euler deconvolution is further applied to estimate the burial depths of the identified structures. The resulting maps highlight high gravity anomalies in the northern part of the study area, suggesting the existence of dense buried formations, likely composed of Eocene and Triassic carbonates. Gravity interpretation also reveals several lineaments with varying orientations and estimated depths ranging between 500 and 1,000 m. The 2.5D gravity model indicates that the Mio-Plio-Quaternary aquifer overlies an Eocene aquifer, and that the detected lineaments may correspond to tectonic faults, which facilitate deep groundwater infiltration and hydraulic contact with Triassic formations. This configuration accounts for the elevated salinities—exceeding 50 g/L—observed in certain localities. Correlation of geoelectrical models with borehole data across different directions highlights notable variations in the depth and thickness of the Mio-Plio-Quaternary water reservoirs, which predominantly align with the gravity-defined lineaments. These findings provide a robust structural basis for understanding groundwater flow paths and salinization patterns in the study area.
Existing applications of the finite element limit equilibrium method (FELEM) have primarily focused on deterministic analyses of simple slopes, with limited attention given to reliability assessments of complex three-dimensional slopes that account for spatial variability and intricate failure mechanisms. To address this gap, a novel 3D FELEM framework based on a rigid finite element formulation is proposed. Three rotational failure mechanisms—spherical, ellipsoidal, and horn-shaped—are incorporated to identify the most critical slip surface in complex terrains. Spatial variability of soil properties is further considered through the Modified Linear Estimation (MLE) method for reliability analysis. Results indicate that the slope length-to-height ratio (L/H) significantly influences stability: for narrow slopes (L/H < 6), 3D safety factors are markedly higher than their 2D counterparts, whereas for long slopes (L/H > 6), the two approaches yield comparable results due to an increased likelihood of localized failure. Among the three failure mechanisms, the horn-shaped mechanism consistently identifies the most critical slip surface and provides the most accurate stability assessments for regular, convex, and multilayer slopes. Reliability analysis further reveals that while both the coefficients of variation of cohesion and friction angle reduce the reliability index, their correlation coefficient exerts an even more pronounced effect. The proposed framework offers a robust and versatile approach for 3D slope stability and reliability evaluation under spatially variable soil conditions.
Tunnel construction in mining and civil engineering is expanding rapidly worldwide. However, excavating tunnels in soft rock under high-stress conditions presents substantial challenges, including large deformations and support system failures, which significantly affect both safety and cost. Current research on effective deformation control measures remains limited, underscoring the need for improved support systems, and particularly the exploration of high-performance tunnel lining materials. To address these issues, this study investigates the characteristics of large deformations in soft rock tunnels and proposes a novel composite support strategy combining “rock + airbag resistance limiter as flexible support + rigid support”, in which a full-section circular lining is overlaid with an airbag resistance limiter to control excessive deformation. The feasibility and effectiveness of this support system were evaluated through laboratory model tests designed to induce large deformations in the surrounding rock, with displacements and strains measured at multiple locations. Experimental results demonstrate that the airbag resistance limiter support system limited the maximum vertical and horizontal deformations of the surrounding rock to −4.40 mm and −3.51 mm, respectively. Additionally, a relatively uniform strain distribution was observed, indicating stable mechanical behavior under the tested conditions. This study preliminarily verifies the feasibility of the proposed support concept in a controlled experimental setting; however, further validation through field applications is required. The findings offer useful experimental insights and a foundation for future research and potential engineering implementations in soft rock tunneling.
Aeolian sand poses a significant hazard to engineering infrastructure in cold regions. While Microbial Induced Calcium Carbonate Precipitation (MICP) offers a promising approach for sand stabilization, its efficacy under the low-temperature conditions prevalent on the Qinghai-Tibet Plateau has remained unexplored. This study systematically investigates the MICP process across a temperature gradient from −5°C to 30°C using solution tests, bacterial activity assays, penetration strength tests, carbonate content measurements, and microstructural analyses. Results indicate that while bacterial activity declined substantially at lower temperatures—exceeding an 83
