Search Results (431)

Volumetric collapse, a critical phenomenon in clayey soils, is characterized by a sudden reduction in volume when subjected to wetting under a specific effective vertical stress. This behavior is primarily caused by the breakdown of cementing bonds between particles in the soil’s interstitial spaces. Our study, which examines the impact of unit weight and wetting on the collapse potential of clayey soils under various stress conditions, has practical implications for geotechnical engineers. We evaluated three-unit weights spanning from loose to compacted states and assessed collapse behavior at various stress levels. Even in the observations of the microstructure under a scanning electron microscope, which corroborated the images, the pathology is evident. The results demonstrate an explicit dependency between unit weight and collapsibility. Statistical analysis revealed that unit weight was the predominant factor influencing the outcomes, with the magnitude of applied stress being identified as a secondary yet notable determinant. Furthermore, the non-linear interactions, as elucidated through ANOVA and Tukey’s HSD tests, serve as instrumental methodologies in this analytical framework. The findings underscore a significant correlation between applied stress and collapse potential, underscoring the crucial role of soil densification in mitigating the risks associated with collapse phenomena. Full article

Groundwater drainage-induced karst collapse is a major geohazard in coal-mining regions of central Hunan, threatening residential safety and infrastructure. This study focuses on the Tuoshan minefield in the Jinzhushan mining area by integrating multi-source field data, including surveys of 170 collapse points, long-term groundwater monitoring at six boreholes, and high-density electrical geophysics. A topographically corrected MODFLOW seepage-field model is developed and calibrated for 2014 (RMSE = 0.32 m; NSE = 0.85) and validated for 2015–2016 (RMSE = 0.41 m; NSE = 0.81). To address the large groundwater-level simulation errors commonly encountered in subtropical hilly karst mining settings, the model incorporates a topographic correction, improving simulation accuracy by 12% relative to an uncorrected model. The simulations capture rapid “steep rise–slow fall” groundwater dynamics: Heavy rainfall (>100 mm/day) raises groundwater levels by 2.8–3.1 m within 2–3 days, whereas pumping (200 m³/h) causes a 1.9–2.2 m decline within one week. A 1.2 km drawdown funnel forms and overlaps with 89% of collapse points, indicating that seepage-field evolution and groundwater-level decline control collapse clustering, with soil suffusion and soil–water–rock interaction acting as key amplifying processes. Based on Terzaghi’s effective stress principle and the Theis solution, a collapse prediction formula is derived and validated using measured events (accuracy = 87.5%), and a region-specific critical hydraulic gradient (i_n = 0.85) is determined, lower than values reported for North China. The proposed workflow provides quantitative thresholds and model-based guidance for karst collapse prevention in subtropical mining areas. Full article

Assembled H-shaped steel strut (AHSS) has been widely applied in deep excavation projects. In this study, the collapse failure of AHSS C1 in a deep excavation project in China was investigated. The collapse of C1 was directly attributed to the settlement of its supporting columns in the mid-span, which was triggered by a nearby pit bottom leakage through an exploration borehole. Then the implementation of the emergency measures and reconstruction works were introduced. Theoretical and numerical pre-assessments confirmed that the reconstructed C1 exhibited adequate safety for strength, in-plane stability and out-of-plane stability, with all steel components and bolts within their safe limits. The good working performance of reconstructed C1 was finally verified through the monitoring results (i.e., strut axial force, soil horizontal displacement, column vertical displacement, road settlement and building settlement) of the foundation pit during the subsequent soil excavation and basement construction. This study is believed to provide references for future excavation projects using AHSS with similar risks. Full article

With the continuous expansion of Pleurotus ostreatus cultivation, substantial quantities of post-harvest spent mushroom substrate (SMS) are generated. Improper disposal of this organic waste poses potential threats to soil health, including contamination and ecological imbalance. Consequently, a rigorous safety assessment is indispensable to support the sustainable and agronomically viable utilization of SMS as a soil amendment. In this study, P. ostreatus SMS was subjected to sterilized and non-sterilized treatments, and a controlled co-culture system integrating P. ostreatus mycelium with wheat was established. This system facilitated a comprehensive evaluation of residual mycelium impacts on wheat growth and development at phenotypic, cytological, and non-targeted metabolomics (LC-MS) levels. Results demonstrated that direct field application of non-sterilized SMS severely compromised wheat performance, inducing root necrosis and significantly reducing grain set. Comparative experiments confirmed that non-sterilized SMS—not its sterilized counterpart—exerted pronounced phytotoxic effects, markedly inhibiting seedling growth and triggering wilting symptoms. To elucidate the temporal dynamics of mycelial interaction, wheat seedlings were inoculated with viable P. ostreatus mycelium and co-cultured for seven days. Under these conditions, the mean root length of the control group (10.82 cm) was approximately threefold that of the treatment group. Histopathological analysis revealed a progressive infection pattern initiating at the root apex and extending basipetally; prolonged exposure ultimately caused complete root system collapse. Scanning electron microscopy further showed extensive mycelial colonization on infected root surfaces, accompanied by characteristic cellular damage—including severe cell wall wrinkling and widespread cell death. LC-MS profiling identified 1867 annotated compounds. Comparative analysis revealed significant dysregulation of secondary metabolism, with 495 metabolites upregulated and 419 metabolites downregulated in the treatment group. Collectively, these findings provide robust evidence that unprocessed P. ostreatus SMS poses tangible agronomic risks upon direct soil application. This study establishes a critical scientific foundation for developing safe, evidence-based protocols for the valorization and integrated management of SMS. Full article

Collapsible soils present significant geotechnical challenges due to their abrupt volume reduction and strength degradation upon wetting, which can lead to severe structural damage. This study evaluates the effectiveness of sustainable and eco-friendly additives—including rice husk ash, lime, eggshell powder, turmeric, polypropylene fibers, nanosilica, and Sarooj mortar—in stabilizing a naturally collapsible clay soil from Gorgan, Iran. A comprehensive experimental program comprising collapse potential, unconfined compressive strength (UCS), and unconsolidated undrained (UU) triaxial tests was conducted. The untreated soil exhibited a high collapse potential of approximately 11.1%, classifying it as severely collapsible. Upon stabilization, the collapse potential was significantly reduced to 1.35–4.63%, representing a reduction of up to ~88%, and reclassifying the soil into slight to moderate collapsibility. In terms of strength improvement, the UCS increased from 0.71 kg/cm² (untreated soil) to values exceeding 3.5–4.3 kg/cm² after 28 days of curing, corresponding to an increase of more than 4–5 times depending on the mixture composition. Additionally, triaxial test results indicated improvements of over 20% in shear strength parameters, including cohesion and friction angle, particularly after 28 days of curing. The observed improvements are attributed to the combined effects of pozzolanic reactions (lime, rice husk ash, nanosilica), cementitious bonding (Sarooj mortar), and mechanical reinforcement (polypropylene fibers), which collectively enhance soil structure, reduce the void ratio, and increase interparticle bonding. Among the tested mixtures, samples containing higher nanosilica and fiber content demonstrated superior performance in both strength and collapse resistance. Overall, the integration of traditional Sarooj mortar with modern eco-friendly additives provides a sustainable and efficient solution for mitigating collapse potential and enhancing the mechanical behavior of clayey soils. The proposed approach offers a low-carbon alternative to conventional stabilization methods, with significant implications for foundation engineering and infrastructure development in regions with problematic soils. Full article

Over six decades, satellite remote sensing of water resources has evolved from manual interpretation of weather photographs to AI systems that learn hydrologic predictions directly from satellite imagery. This review traces that evolution through the observation-to-inference arc—a framework for the progressively tightening coupling between what satellites observe and what hydrologists infer. Using illustrative applications in precipitation, evapotranspiration, soil moisture, snow, surface water, and groundwater, we show how early observations (1960–1985) remained disconnected from operational hydrology; how calibrated retrieval algorithms (1985–2000) established a one-way pipeline from satellites to models; how operational infrastructure (2000–2015), anchored by MODIS, GRACE, GPM, and Sentinel, achieved assimilative coupling through computational feedback between models and observations; and how deep learning (2015–present) is beginning to collapse this pipeline. Multi-source data fusion has been a recurring enabler at each stage. We articulate a four-level AI vision and research trajectory, from AI-assisted interpretation through AI-native retrieval and AI-driven inference to autonomous Earth observation intelligence. Persistent challenges in mission continuity, calibration, equity of access, and translating satellite-derived information into operational water management decisions provide essential context for evaluating both the promise and limits of this trajectory. Full article

Excessive planting density and heavy rainfall weather threatens global agriculture, particularly affecting maize. Biochar is an environmentally friendly soil amendment that has a yield-increasing effect. However, the regulatory mechanism of biochar frequency on crop internode development and photosystem II photosynthetic efficiency remains unknown. A total of nine treatments were followed in this experiment. Three applications of biochar were as follows: no biochar application (B0); biochar application at 4.2 t ha⁻¹ year⁻¹ (B1); and biochar application at 8.4 t ha⁻¹ 2 year⁻¹ (B2), alongside three nitrogen (N) fertilizer rates (0, N0; 180 kg ha⁻¹, N1 and 225 kg ha⁻¹, N2). The results showed that the internode thickness of the 2nd to 5th nodes under N2B2 treatment increased by 17.7%, 16.0%, 19.7%, and 21.7%, respectively, compared to N0B0. Annual biochar application had a higher stem diameter coefficient for the 1st to 3rd nodes than no biochar (B0) and treatments applied every two years (B2). Annual biochar application had the highest dry weight of internodes and plant height compared with B0 and B2. The relative chlorophyll content of leaves was significantly increased by biochar combined with N fertilizer or by N fertilizer alone. Biochar combined with N fertilizer significantly reduced NPQt and ΦNPQ, which were reduced by 59% and 50%, respectively, under N2B1 treatment compared with N0B0. The N2B1 treatment increased ΦII by 30% compared to N0B0. Stem diameter coefficient was significantly negatively correlated with NPQt and ΦNPQ and significantly positively correlated with ΦII and Fv/Fm. Compared to B1, B2 increased the maize yield. Annual biochar application combined with N fertilizer reduced stem collapse and enhanced post-flowering photosynthesis. Overall, considering the yield traits, 8.4 t ha⁻¹ biochar application combined with 180 kg ha⁻¹ N fertilizer treatment was the best. This study will provide reference data for cultivation regulation to enhance maize’s resistance to collapse and maintain photosynthetic capacity. Full article

Biosurfactant-producing microorganisms play an important ecological role in soils impacted by hydrophobic contaminants by enhancing substrate bioavailability and influencing microbial interactions. In this study, we critically evaluated the reliability of commonly used screening methods for biosurfactant detection. A total of 71 microbial isolates (16 bacteria and 55 fungi) were obtained from vegetable oil-contaminated soil and screened using a multi-step approach combining enzymatic assays (lipolytic and hemolytic activity) and physicochemical methods, including drop-collapse, oil spreading, emulsification index (E₂₄), and surface tension reduction. Although 21 isolates exhibited lipolytic activity and 9 showed hemolysis, inconsistent responses among assays revealed significant limitations of individual screening methods. Only two bacterial isolates consistently tested positive across all criteria. When cultivated in mineral salt medium supplemented with hydrophobic substrates, both isolates produced stable emulsions and significantly reduced surface tension (from 54.26 mN/m to 31.46 mN/m). Substrate-dependent variation was observed for isolate C3, which showed reduced surface tension (39.63 mN/m) when grown with biodiesel. These findings highlight the risk of relying on single assays and emphasize the need for integrated screening strategies to ensure reliable detection of biosurfactant-producing microorganisms. Full article

Non-cohesive earth dams are widely distributed in natural and semi-engineering scenarios, and overtopping-induced breaches are their most catastrophic failure mode. Accurate prediction of the overtopping failure process and breach evolution is critical for risk assessment, emergency management, and dam design optimization. In this study, an improved 3D numerical method is developed to simulate the coupled hydrodynamic–erosion–breach evolution processes of non-cohesive earth dams. The model based on the finite volume method integrates three core modules: a hydrodynamic module based on the Reynolds-Averaged Navier–Stokes equations with the Volume of Fluid method for free surface tracking, a dam material erosion module considering particle entrainment and transport mechanisms of non-cohesive soils, and a breach development module coupling erosion and gravitational collapse. To validate the model, two levels of verification are conducted: first, a classic benchmark dam break case is employed to confirm the feasibility of the hydrodynamic and breach evolution algorithms; second, published flume experimental data of non-cohesive earth dam overtopping failures are adopted to evaluate the model accuracy in predicting breach hydrographs and spatiotemporal evolution of breach geometry. The results demonstrate that the proposed model accurately reproduces the key characteristics of overtopping failure with high fidelity. The predicted breach flow rates and flow depths are in excellent agreement with experimental observations, with relative errors less than 5% for both peak discharge and time to peak. Consequently, this study provides a reliable numerical tool for detailed simulation of non-cohesive earth dam breaches and offers scientific support for emergency management. Full article

Circular pipe-jacking construction in gravel strata faces significant technical challenges, including high frictional resistance, elevated permeability, and susceptibility to collapse. Optimizing the formulation of thixotropic slurry is crucial for improving the construction quality and efficiency of such projects. This study, based on the Ruyang Water Supply Project of the North Main Canal in the Qianping Irrigation Area, Henan Province, China, systematically investigated slurry formulation using bentonite, soda ash, sodium carboxymethyl cellulose (CMC), polyacrylamide (PAM), and shell powder as raw materials. An orthogonal experimental design was employed to optimize the mix proportions, and the friction-reduction performance was validated through drag-friction model tests. The results indicate that the optimal slurry formulation is: bentonite 8%, soda ash 0.3%, CMC 0.2%, PAM 0.15%, shell powder 4%, and water 87.35%. This formulation exhibits excellent fluidity and thixotropy, facilitating the formation of a stable slurry film. Consequently, the friction coefficient between concrete specimens and gravel soil was reduced by 35.6%. The inclusion of shell powder significantly enhanced the slurry’s cohesiveness and improved the anti-seepage capacity of the surrounding stratum due to its filling effect. The optimized thixotropic slurry effectively mitigates frictional resistance during pipe jacking in gravel strata and enhances the formation’s resistance to collapse. The findings of this study provide a viable technical reference for pipe-jacking projects under similar geological conditions. Full article

Tunnels are critical components of transportation networks. Explosions caused by accidents or terrorist attacks can severely damage tunnel linings and even cause structural collapse. This paper develops the validated simulation model for single-channel tunnels into a twin-channel tunnel model. Subsequently, a simulation study investigates the damage state and vulnerability of the twin-channel tunnel under single-sided internal blasting. The results suggest that the supporting effect of the soil can improve the blast resistance of the outer wall of the tunnel. An explosion within a single channel can induce changes in the relative bearing capacity of the twin-channel lining. Under the influence of earth pressure, the relative bearing capacity of the twin-channel lining is further weakened, thereby affecting the overall failure state of the tunnel. Longitudinal plastic strain is primarily distributed at the ends and center of walls and floors, and it spreads as the charge mass increases. The charge location has a significant impact on the damage state of the outside walls of the uncharged channel of the tunnel. Placing explosives on tunnel walls will increase the damage level of the twin-channel tunnel. When the charge weight exceeds 1000 kg and 3000 kg, respectively, the exceedance probability for minor damage and severe damage to the tunnel approaches 1. The strengthening of the blast protection level of the center wall is the key to preventing tunnel collapse. Full article

Hatay (Ancient Antioch), one of Türkiye’s most historically significant and seismically active provinces, experienced extensive damage during the 6 February 2023 Kahramanmaraş earthquake sequence (Mw = 7.7 and Mw = 7.6) and its aftershocks. Among the affected structures, masonry mosques and minarets suffered critical damage, revealing significant seismic vulnerabilities. This study provides a comprehensive evaluation of the seismic performance and structural vulnerabilities of masonry mosques and minarets in Hatay following the devastating 2023 Kahramanmaraş earthquake sequence. By integrating extensive field observations with advanced numerical analysis, the research documents widespread damage to both traditional kiosk-style and classical minarets, identifying critical factors such as poor local soil conditions, insufficient material strength, and lack of engineering services that contributed to structural collapses, including that of the historic Habibi Neccar Mosque. Through finite element analysis (FEA) using ABAQUS, the study compares different material configurations to assess nonlinear dynamic responses under representative seismic excitations, revealing that recorded ground motions in Hatay significantly exceeded current design-level spectra. The findings offer vital insights for the seismic assessment, retrofitting, and preservation of irreplaceable cultural and religious heritage structures in seismically active regions. This study addresses the enhancement of seismic resistance to historical structures not merely as a safety issue, but also as a social sustainability element that ensures the transmission of cultural heritage to future generations. Full article

To address the potential threat of surface subsidence caused by coal mining to the safe operation of buried gas pipelines in goaf collapse areas, this study investigates the geological conditions of the Mugu Coal Mine in Shanxi Province, China, and a gas pipeline passing through its surface mining area. Using a combination of numerical simulations and physical analog modeling, the mechanical response and deformation characteristics of the pipeline under mining-induced influences were systematically analyzed from three perspectives: the failure mechanisms of surface soil, the pipe–soil interaction behavior, and the damage evolution of the pipeline within the goaf. The research reveals a separation-induced failure pattern of the gas pipeline in mining-affected areas, referring to the mechanism in which differential settlement causes pipe–soil detachment, leading to unsupported bending deformation and stress concentration. Results show that the subsidence basin expands rapidly when the working face advances between 150 m and 210 m. Before this stage, the pipeline and surface soil deform synergistically with a symmetric subsidence curve centered on the goaf and uniformly distributed loads, showing no significant damage. During this stage, non-synergistic deformation occurs, leading to separation between the pipeline and soil. The maximum subsidence point shifts away from the center, destroying symmetry and causing stress concentration at the mining boundary, the advancing working face, and the goaf center, resulting in severe bending and rapid failure. After this stage, the pipe–soil interaction restabilizes with reduced separation height and extent, though pipeline deformation and damage continue to increase gradually. These findings provide a theoretical basis for engineering design optimization, targeted reinforcement measures, and monitoring strategies for gas pipelines in similar goaf collapse areas. Full article

This study examines the seismic stability of an underground powerhouse cavern located in the Lesser Himalayan region of Nepal. Both static and seismic loading conditions are analyzed using the finite element method (FEM) and the distinct element method (DEM). Rock mass properties are derived from field investigations and laboratory testing, while empirical correlations are applied to estimate rock mass strength and deformation modulus. Pseudo-static analyses are performed using the FEM-based software Rock and Soil-2-Dimensionsl (RS²) Version 11.027, and dynamic analyses are conducted using the DEM-based software Universal Distinct Element Code (UDEC) Version 5.0 to evaluate deformation and stress redistribution around the cavern. Seismic fragility curves are developed to quantify the probability of damage under varying seismic intensities. Results indicate that a peak ground acceleration (PGA) of 0.25 g increases cavern wall deformation by approximately 15–20 mm compared to static conditions. Fragility analysis shows a probability exceeding 68% for slight damage, while the probability of collapse remains low at approximately 1.7%. Seismic loading also significantly alters stress redistribution along the cavern boundary. Overall, the combined use of numerical modeling and fragility analysis provides a probabilistic framework for assessing seismic risk in underground caverns, offering valuable insights for the design and safety evaluation of hydropower projects in seismically active Himalayan regions. Full article

To clarify the differences in and mechanisms of soil detachment before and after soil collapse, five typical granite soil layers (red soil, red soil–sandy soil, sandy soil, sandy soil–debris, and debris layers) of Benggang in Anxi County, Fujian Province, were studied via laboratory runoff scouring tests, and the detachment capabilities and influencing factors of undisturbed (original) and disturbed (colluvial deposit) soils were compared. The results showed that disturbance due to soil collapse significantly increases the soil detachment capacity by an average of 1046 times, with the greatest increase occurring in the red soil–sand soil layer (3494 times) and the smallest increase occurring in the debris layer (63 times). The undisturbed soil detachment capacity increases with increasing soil depth, whereas the disturbed soil capacity first increases but then decreases, with the sand layer having the highest capacity. Hydrodynamic fitting results revealed that undisturbed red soil has a linear relationship, red soil–sandy soil and sandy soil layers have power function relationships, and sandy soil–debris and debris layers have logarithmic relationships with flow shear stress. Disturbed red soil and red soil–sandy soil layers are linearly related, whereas the other layers are logarithmically related. Correlation analysis revealed that undisturbed soil detachment is significantly negatively correlated with clay, silt, gravel, free iron oxide, and free alumina contents and positively correlated with sand content. Disturbed soil shows similar correlations, but it has a negative correlation with organic matter instead of gravel. Structural equation modelling (SEM) path analysis revealed that undisturbed soil detachment is affected mainly by negative free alumina oxide content (path coefficient of −0.87) and flow shear stress (path coefficient of 0.14), whereas disturbed soil is controlled mainly by negative shear strength (path coefficient of −0.76) and positive flow shear stress (path coefficient of 0.49). This study elucidates the mechanism by which colluvial deposit disturbance accelerates soil detachment, providing a theoretical basis for the prevention and control of Benggang erosion in the hilly regions of southern China with red soil. Moreover, the comparative research strategy adopted in this study offers a reference for related investigations in similar erosion-prone areas. Full article