The disaster-forming environment of post-earthquake debris flows in mountainous areas exhibits staged evolution.Traditional debris flow susceptibility assessments mostly rely on random sampling or cross-validation,which is difficult to test the inter-temporal prediction ability and transferability of models.To solve this problem,this paper introduces a temporal-extrapolation validation framework to carry out dynamic susceptibility assessment of post-earthquake debris flows.Taking Yingxiu Town,Wenchuan County,Sichuan Province as the study area,three clustered debris flow events(the"8·13"event in 2010,the"7·10"event in 2013,and the"8·20"event in 2019)were selected to construct an event-scenario susceptibility index system including stable factors and time-varying factors.The random forest model was used,and key factors were screened through feature importance.A decision threshold optimization strategy integrating recall and precision was proposed.The model was trained with samples from 2010 and 2013,and extrapolated to the 2019 event for independent validation.The results show that after threshold optimization,the model performance on the test set is:Re=0.90,Pre=0.41,F1=0.56.Compared with the original threshold(Pre=0.33,F1=0.48),the Pre is increased by 24％and F1 by 17％after calibration.This strategy effectively improves the reliability of early warning information and can significantly reduce unnecessary early warnings and resource consumption.In addition,the spatial distribution of high and very high susceptibility zones varies significantly over time,and actual debris flow are mostly located in such watersheds.The susceptibility assessment framework proposed in this study provides a feasible technical solution for cross-temporal identification of post-earthquake debris flows,and can provide a reference for dynamic susceptibility assessment of post-earthquake debris flows.
The upper reaches of the Lancang River represent a critical geomorphic transition zone from the Qinghai-Xizang Plateau to the Yunnan-Guizhou Plateau.The distinctive alternation of high mountain gorges and wide valleys in this region leads to frequent landslides,severely constraining sustainable socio-economic development.However,landslide monitoring studies in this area remain limited.Moreover,in existing hazard genesis attribution analyses,precipitation,a key triggering factor,is often oversimplified by correlation-based approaches,which fail to capture its non-linear spatiotemporal driving effects and lagged responses,thereby hindering quantitative interpretation of the underlying physical mechanisms.This study proposed an integrated research framework combining multi-source remote sensing-based collaborative monitoring with causal discovery.First,ascending and descending Sentinel-1 SAR data together with high-resolution optical imagery were used to perform regional early identification and high-precision time-series deformation monitoring of active landslides using the small baseline subset InSAR(SBAS-InSAR)technique,followed by analysis of their spatial distribution characteristics.Subsequently,long time-series deformation data from two representative landslides with distinct geomorphic and deformation characteristics were selected,and sequential variational mode decomposition(SVMD)method was applied to separate periodic and trend components.Finally,to overcome the limitations of correlation analysis in identifying nonlinear lagged causality,the convergent cross mapping(CCM)method was introduced to quantitatively diagnose the causal driving strength between precipitation and periodic landslide deformation,as well as the optimal lag time.The results indicate that:(1)Joint ascending-descending observations detected maximum line-of-sight deformation rates of-83 mm/a and-96 mm/a(negative values represent subsidence),respectively,and identified a total of 3 009 active landslides.(2)Active landslides exhibited significant spatial clustering,predominantly concentrated on steep slopes,within fault-influenced zones,and near river systems and transportation corridors.(3)The CCM method successfully captured the optimal lag effect between precipitation and periodic landslide deformation,with an optimal lag of 36 days for the Xiangda village landslide.The CCM method effectively reveals the causal relationship between precipitation and deformation and its optimal lag,providing a better representation of the non-linear physical mechanisms governing evolution of complex landslide systems.This research not only expands the technical means for analyzing landslide deformation mechanisms in complex terrains but,more importantly,validates the applicability and strong potential of the proposed integrated framework combining multi-source remote sensing collaborative monitoring and causal analysis for deciphering the driving mechanisms of key factors in geological hazards.The findings provide a data-driven scientific support for elucidating the physical driving mechanisms and performing dynamic risk assessments of landslides in complex geomorphic regions.
Debris flows carrying large boulders often cause more severe damage to buildings and structures than conventional debris flows. The “August 3” extreme large debris flow in Ridi gully carried large boulders, destroyed an expressway bridge, buried houses, and blocked the Kangding River. Based on field investigation and existing research results on large boulders in debris flows, this paper analyzes the disaster-causing characteristics of the debris flow. It also explores the distribution, impact characteristics and causes of large boulders in combination with UAV aerial survey images, and puts forward corresponding prevention and control suggestions. The impact force of debris flow slurry in Ridi gully is 102.39 kN, and the maximum impact force of large boulders is 30638.54 kN, which can be more than 300 times that of slurry. Collapses and landslides are extremely developed in the Ridi gully basin, with 16 landslides and 157 collapses. The debris flow discharge is large, and the peak debris flow discharge at the broken bridge can reach 1600 m3/s. The distribution density of large boulders is positively correlated with the development degree of collapses and landslides in the basin. Frequent earthquakes intensify the development of collapses and landslides and promote the formation of large boulders. New mountain fissures exist in the Ridi gully basin, which is under great threat of mountain collapse and landslide.
Three-dimensional(3D)deformation monitoring of landslides is a key indicator for understanding their kinematic mechanisms and potential hazard risk.Taking the Malan landslide in Tianshui,China,as a case study,this paper employs InSAR-based 3D decomposition combined with rainfall-deformation coupling analysis to reveal the 3D deformation characteristics of the slope and its response to rainfall.Time-series Sentinel-1A ascending and descending SAR images acquired from July 2022 to July 2025 were processed using the SBAS-InSAR method to derive surface deformation series.A slope-aspect-constrained 3D decomposition model was then applied to retrieve deformation rates and cumulative displacements in the vertical,east-west and north-south directions.Based on this,typical profiles and representative points were extracted;the evolution stages of the landslide were characterized using the tangent angle of displacement-time curves,and wavelet coherence analysis with regional rainfall records was conducted to quantitatively assess the influence of rainfall on 3D deformation.(1)The 3D deformation field reveals an asymmetric composite sliding mode dominated by vertical subsidence with superimposed east-west horizontal motion.The maximum cumulative horizontal and vertical displacements reach 52 mm and 14 mm,respectively.The deforming area exhibits stage-wise intensification and marked spatial heterogeneity.(2)Wavelet coherence analysis between 3D point-wise displacement and rainfall indicates that vertical deformation exhibits strong coherence with rainfall at periods of 1-4 months,with coherence coefficients generally greater than 0.8.The phase relationship indicates that rainfall leads deformation by approximately 1-2 months.The east-west component shows scale-dependent coupling with rainfall,whereas the north-south component exhibits relatively weak coherence.Combined analysis of displacement-rainfall time series and tangent-angle evolution further demonstrates that intense summer rainfall events in 2023 and 2024 temporally coincide with multiple acceleration phases of the landslide.Seasonal heavy rainfall is the primary external factor influencing the enhancement of vertical subsidence and east-west sliding of the Malan landslide,which displays distinct stage-wise evolution during the monitoring period.The proposed methodology provides technical support and a methodological reference for refined 3D deformation characterization and early warning of rainfall-affected landslides.
Loess-red bed interface landslides occur frequently in Northwest China, and the critical conditions for their initiation are closely related to the dynamic evolution of the shear strength at the contact interface. To investigate the initiation mechanisms of such landslides, this study takes the slip zone soils of typical loess-red bed interface landslides as research objects. Through ring shear tests and scanning electron microscopy (SEM) analyses conducted on three types of samples (pure loess, pure red bed, and loess-red bed composites) the study systematically evaluates the evolution of shear strength and microscopic structures under varying normal stresses, water contents, and shear rates. The results show that: (1) The peak and residual shear strengths of all three soil types increase markedly with increasing normal stress. The peak shear strength exhibits a unimodal variation with water content and shows a slight increasing trend with increasing shear rate. (2) The loess-red bed composite samples are most sensitive to water content changes, with the most significant strength attenuation. Their brittleness index reaches 15.6%, significantly higher than that of the single-component soils, indicating a stronger tendency toward strain-softening failure. (3) Microscopic observations reveal that increasing water content weakens cementation of clay particles, and the enhanced lubricating of flaky minerals promotes the formation of smooth shear surfaces, leading to a significant reduction in interfacial shear strength. Integrating field investigations with laboratory tests, the initiation mechanism of loess-red bed interface landslides is clarified. The hydraulic weakening effect of the loess-red bed interface is identified as the core mechanism controlling slope instability.
The extreme rainstorm in July 2023 triggered widespread debris flows on both sides of Jiulong Mountain in Mentougou district, Beijing, causing severe losses. Accurate identification of post-rainstorm debris and analysis of their formation mechanisms are urgently needed to support post-disaster reconstruction and hazard prevention in the area. Taking the areas on both sides of Jiulong Mountain as the study area, 12.5 m resolution ALOS PALSAR DEM data and 0.3 m resolution Maxar WorldView pre- and post-rainstorm imagery were used. River network vectors were extracted via ArcGIS, and the Visible Atmospherically Resistant Index (VARI) was applied to detect vegetation changes. Manual visual interpretation was supplemented to identify debris flow gullies. Topographic parameters of gullies were extracted, and regional geological data were integrated to analyze debris flow controlling factors. A total of 8 debris flow gullies were identified, with catchment areas of 1.20 to 5.54 km2, main channel lengths of 1646.8 to 3838.0 m, and average longitudinal gradients of 204.3‰ to 339.9‰. The distribution of debris flows is controlled by the Jiulong Mountain compound syncline and the northern fault zone. The Yaopo Formation coal-bearing strata and coal mining waste provide abundant loose materials. Post-rainstorm vegetation cover decreased significantly, with exposed soil and rock widely distributed. Combining high-resolution DEM-derived gully boundaries with VARI change maps derived from high-resolution images before and after the rainstorm improves the efficiency and accuracy of debris flow gully identification. The overall accuracy and precision reach 80%, with a recall rate is 100%. This method reduces misjudgments from DEM-only river network extraction and has strong application value.
In the process of deep-buried coal seam mining, underground water inrush disasters are closely related to the distribution patterns and development degree of faults. However, the quantitative relationship and internal mechanisms between them are still scientific problems that urgently need to be solved in the field of mine water disaster prevention and control. Considering the combined relationships among the evaluation indeces of fault complexity, a quantitative evaluation model of fault complexity in coal-bearing strata is constructed by combining game theory, variable weight theory, and the cloud model. Fault density, fault fractal dimension, densities of fault pinch-out points and intersection points, and the fault strength index are selected as the main controlling factors of fault complexity, and contour maps of the spatial distribution of each factor are obtained. The model divides the fault complexity in study area into simple, relatively simple, medium, relatively complex, and complex zones, with respective proportions of 2.3%, 20.7%, 38.0%, 32.5%, and 6.5%. The fault complexity index (FCI) is significantly negatively correlated with the core recovery ratio (CRR) (R2 = 0.7594 ), which verifies the accuracy of the model. The result also reveal that both the locations of mine water inrush points and the intensity of water inrush are significantly positively correlated with the complexity of fault structures. The research results can provide a theoretical basis for mine water disaster prevention and control in areas with well-developed fault structures.
During flash flood formation, abundant loose materials produced by rainfall-induced landslides and slope erosion enter the river channel with runoff, significantly altering flood routing characteristics and transforming into flash flood and debris flow disasters. On June 26, 2020, short-duration intense rainfall combined with steep terrain triggered local landslides and catastrophic flash flood-debris flow events in the Caogu River Basin, Mianning County. To investigate the impact of landslide-induced sediment supply on the evolution of flash flood-debris flows, this study adopted a numerical simulation approach to analyze the distribution of potential landslide sediment sources in the Caogu River Basin under short-duration heavy rainfall. The propagation process of flash flood-debris flows was simulated using the spatial boundary of landslide sediment sources, and the effect of landslide-derived sediment on disaster formation was further examined. Results show that the short-duration intense rainfall triggered numerous landslides, which were mostly distributed along both sides of gullies. The northern gully provided a particular large volume of loose sediment. After discharging from the gully, flow velocity dropped abruptly due to a sudden decrease in channel gradient, resulting in massive sedimentation that ultimately caused river diversion and inundation of downstream villages. The findings reveal the key controlling effect of landslide sediment supply on the formation of flash flood-debris flow disasters, and provide a scientific basis for the prevention and mitigation of such hazards in mountainous areas of southwestern China.
On July 4, 2023, a high-elevation rock avalanche-debris flow occurred in Yitougou, Changtan Town, Wanzhou District, Chongqing, threatening the lives of 408 residents. To enhance the understanding of the dynamic mechanisms governing such high-altitude rock avalanches, this study conducted a numerical simulation of the event using the smoothed particle hydrodynamics (SPH) method integrated with a modified Johnson-Cook (MJC) constitutive model within the self-developed LPF3D simulation platform. The simulation results indicate that the motion process of the avalanche-debris flow can be divided into four distinct stages: (1) weakening of the slope due to external disturbances; (2) frontal traction and initial acceleration; (3) middle-rear compression and fragmentation; and (4) energy dissipation and final deposition. Furthermore, the study reveals that the shear-induced fragmentation of the rock mass and its subsequent transformation into a debris flow are key mechanisms driving the high-speed and long-runout movement. This research not only deepens the theoretical insights into the dynamics of high-elevation rock avalanches but also provides quantitative support for hazard assessment and spatial prediction of similar events in mountainous regions.
To supplement the engineering property data of undisturbed soft plastic clay in Kunming, this study systematically measures its physical and mechanical parameters via laboratory tests to reveal the evolution laws of physical properties, consolidation deformation, shear strength, and permeability. A series of laboratory tests were performed on undisturbed soft plastic clay samples collected from the foundation pit excavation of the northwest new city digital economy industrial park project in Wuhua district, Kunming. The basic physical properties, consolidation-deformation characteristics, shear strength, and permeability of the soft-plastic soil were analyzed. The results indicate that the soft plastic clay is characterized by high natural water content, high compressibility, and low shear strength, indicating unfavorable engineering properties. The consolidation coefficient reaches its peak at approximately 100 kPa, presenting an obvious stress-dependent feature. The permeability coefficient is at a medium-low level and decreases with the increase of consolidation stress and the decrease of void ratio. The parameters obtained can provide data support for engineering analysis of similar soils. The nonlinear variation of the consolidation coefficient and the correlation mechanism between permeability coefficient, stress, and void ratio provide a theoretical basis and parametric reference for solving problems such as “large excavation rebound and difficult-to-control support deformation” in soft soil foundation and foundation pit engineering in the Dianchi Lake basin.
High-fill slope engineering is common in the construction of airports in plateau mountainous areas of China.Influenced by the plateau climate and complex topography,the stability and failure mechanisms of such high-fill slopes are complicated,especially under adverse conditions such as extreme rainfall.The interaction between geomaterials and retaining structures exhibits strong nonlinearity.This study aims to develop an effective approach for accurately analyzing the stability and failure mechanisms of such slopes.The material point method(MPM)high-performance computing software CoSim-MPM was employed,and the strength reduction method(SRM)was incorporated to evaluate slope stability and investigate the failure process.Taking a high-fill retaining wall slope at a mountainous airport as a case study,a systematic analysis was conducted on its stability and failure mechanisms under natural and heavy rainfall conditions.The results show that the slope remains generally stable under both natural and rainfall conditions;however,the failure modes differ.Under natural conditions,the slope exhibits a push-type failure,while under heavy rainfall conditions,it shows a traction-type failure.The findings demonstrate that the proposed approach offers significant advantages for studying the stability and failure mechanisms of high-fill slopes,providing a scientific basis for the site selection,design,and risk assessment of similar engineering projects.
On August 7,2025,a catastrophic flash flood triggered by extreme rainfall struck Yuzhong County,Gansu Province,exhibiting a typical"flash flood-debris flow-flash flood"cascading disaster chain.To address the challenge of reconstructing cascading processes of flash flood disasters under frequent extreme weather,this study takes this event as an example to establish and verify a technical process integrating multi-source remote sensing and hydrodynamic models.By combining observed data from meteorological stations with the ERA5-Land reanalysis dataset,a detailed reconstruction of the rainfall process in the upstream debris flow initiation zone was achieved.Subsequently,the HEC-RAS 2D hydrodynamic model was adopted to reconstruct the inundation process in the downstream floodplain area based on topographic data,land use information,and remote sensing-based disaster extents.The results indicate that:(1)ERA5-Land data effectively captures the spatial distribution and cumulative trend of rainfall,but systematically underestimates short-duration extreme rainfall intensity,with peak rainfall in the study area differing by a factor of 5 to 8 from observed values;(2)the HEC-RAS model constructed with 12.5 m resolution ALOS PALSAR DEM effectively reproduces flood propagation paths and the main inundation extent,and simulation results are highly consistent with actual disaster extents extracted from post-event high-resolution satellite imagery.Local discrepancies are mainly attributed to topographic data accuracy and the influence of human engineering activities on surface parameters.In summary,the integrated"data-simulation-reconstruction"analytical framework proposed in this study demonstrates the dual role of multi-source remote sensing in both driving and validating the reconstruction process of flash flood disasters,providing a technical pathway and scientific reference for early warning and quantitative assessment of small-watershed disasters.
This paper provides a systematic review of the dynamic erosion mechanisms and research progress of ultra-high-level long-runout landslides.Key differences between ultra-high-level and general high-position long-runout landslides are highlighted,and the historical development of studies on high-level landslide motion mechanisms is systematically summarized.Based on representative cases,three dominant erosion effects-excess pore water pressure-induced erosion,impact loading erosion,and plowing erosion-are analyzed with respect to their characteristics and underlying causes.Advances in simulation approaches,including physical model tests,laboratory experiments,and numerical simulations,are also discussed.Building on previous research,this study identifies key challenges that remain in the field,including the acquisition of dynamic monitoring data in ultra-high-level mountainous areas,the accuracy of chain hazard simulations,and the clarification of the relationship between energy transfer and erosion intensity.The importance of field-based geological surveys is also underscored.Looking ahead,the integration of emerging technologies such as artificial intelligence and realistic 3D simulations is expected to enable multidisciplinary collaboration and multi-model coupling,thereby opening new avenues for future research.
Karst damage is a key internal trigger controlling the instability of limestone slopes.To deeply reveal the mechanical response characteristics and failure mechanism of limestone containing cavities,this study adopted multi-scale research methods including uniaxial compression tests,PFC3D discrete element simulations,digital image correlation technology,and discrete element numerical inversion.The coupling mechanism of different numbers of circular cavities(1-4)and spatial arrangements(transverse/vertical)on the mechanical properties,degradation laws,and failure modes of limestone was quantitatively analyzed.The results show that the peak strength,elastic modulus,and peak strain of transversely arranged specimens exhibit exponential attenuation characteristics,while vertically arranged specimens show a linear decreasing pattern,with the deterioration effect of transverse arrangement on strength parameters being 37.2％higher than that of vertical arrangement.Single-cavity specimens exhibit typical diagonal shear failure,while multi-cavity specimens(n≥2)evolve into vertical through-going splitting failure.When the number of circular cavities increases from 1 to 4,the crack initiation stress significantly decreases from 166.86 MPa to 154.32 MPa,a reduction of 12.5％.This study establishes a nonlinear attenuation model between the number of circular cavities and peak strength,reveals the strength degradation laws under different arrangements,and verifies the directional control effect of circular cavity spatial configuration on failure modes.The research results provide theoretical basis and technical support for the stability evaluation of engineering rock masses and the prevention of geological disasters in karst areas.
Rock and soil masses are significantly affected by thermal-wet cycles,and the resulting changes in their internal structure and strength poses a serious threat to cavern stability.In this study,sandstone samples from Tongchuan City,Shaanxi Province were subjected to continuous thermal-wet cycles tests until failure.The variation in physical properties and acoustic emission characteristics after different number of cycles were analyzed to investigate the damage mechanism induced by thermal-wet cycling.The research results indicate with increasing cycle numbers,the mass loss rate of sandstone first increases and then decreases,while surface roughness increases continuously from 0.043 to 0.214.The number of micropores(r<0.1 μm)decreases,mesopores(0.1 μm1 μm)remain almost unchanged.After 20 cycles,cracks began to appear on the sample surface and rapidly develop,penetrating the entire sample at 70 cycles.The thermal acoustic emission activity of sandstone is significantly enhanced with cycling,and the changes in acoustic emission characteristics can be divided into three stages:Stage I(0-200 s),microcracks expand slowly and stably,with few ringing counts,a gradual increase in cumulative counts,and b-values fluctuating within a limited range;Stage Ⅱ(200-700 s),microcracks undergo unstable propagation,with increased acoustic emission activity and ringing counts,and a rapid increase in cumulative ringing count with frequent and significant fluctuations in acoustic emission b value.Stage Ⅲ(700-900 s),sandstone failure becomes essentially stable,acoustic emission activity and ringing counts decline,cumulative counts plateau,and b-values decrease.A strong correlation is observed between mass loss rate,surface roughness,and the total number of AE signals.The research reveals the damage evolution mechanism of sandstone under cyclic thermal-humid conditions.The findings provide a scientific basis for the protection of ancient cavern rock masses.
Dingjie County in Xizang is located in a high-altitude region characterized by complex geological conditions,active tectonics,and frequent geological hazards.Conducting a regional susceptibility assessment of geological hazards is therefore critical for effective disaster prevention and mitigation.Focusing on Dingjie County,this study establishes a susceptibility evaluation framework based on ten influencing factors:elevation,slope gradient,lithology,terrain relief,distance to fault zones,distance to rivers,distance to roads,mean annual NDVI,mean annual precipitation,and settlement kernel density.These factors form the basis for constructing a geological hazard susceptibility evaluation index system.First,the geographic detector method was applied to quantify the explanatory power of each factor with respect to hazard susceptibility.To address the limit availability of hazard inventory data,a generative adversarial network(GAN)was employed to augment training samples.Subsequently,a GAN-enhanced Random Forest(GAN-RF)model was developed to produce a five-class susceptibility map:low susceptibility,relatively low susceptibility,moderate susceptibility,relatively high susceptibility,and high susceptibility.Finally,model validation and SHAP visualization were conducted to assess model performance.Geodetector results indicate that elevation,mean annual precipitation,and settlement kernel density are the dominant controlling factors.Model validation shows that while the traditional Random Forest(RF)model achieved an AUC of 0.897,the GAN-RF model significantly improved this to 0.953,markedly enhancing the accuracy of identifying high-susceptibility zones.Notably,the high-risk zones,covering only 1.40％of the county area,concentrated 85.81％of the verified geological hazard points.The GAN-RF model effectively improves susceptibility mapping accuracy in high-altitude regions,particularly optimizing the identification of high-risk zones.SHAP validation confirms its effectiveness in evaluating such areas,providing reliable basis for disaster prevention and mitigation decisions.
The mountainous areas of Beijing exhibit a complex geological environment and are prone to frequent sudden geological hazards,posing significant threats to ecological security and to the safety of lives and property.This study aims to systematically analyze the spatial coupling relationships among geological hazards and their controlling factors-spanning geology,topography,and environmental conditions-and to develop a robust susceptibility assessment model to support regional disaster prevention,mitigation,and risk management.Based on the spatial distribution of 9 147 potential geological hazard sites in the mountainous regions of Beijing,nine influencing factors were selected from three dimensions-geological,geographic,and environmental:elevation,slope,aspect,curvature,distance to faults,distance to fold axes,stratigraphy,rainfall in 2024,and NDVI.An improved frequency ratio method was employed to develop the geological hazard susceptibility assessment model.The susceptibilities of collapse,landslide,and debris flow were comprehensively evaluated using the"maximum-value principle"(i.e.,assigning the highest susceptibility class at each location).Factor intervals exhibiting strong positive correlations with hazard occurrence include elevation(150-450 m),slope(5°-28°),aspect(90°-270°),distance to faults(0-2,000 m),distance to fold axes(0-13 000 m),rainfall in 2024(750-840 mm),and NDVI(0.38-0.85).The comprehensive susceptibility assessment results indicate that high-susceptibility zones covers 2 634.636 km2,accounting for 26.08％of the total study area.These zones are mainly distributed around the Miyun Reservoir in central Miyun district,the southern and central-eastern parts of Huairou district,the piedmont areas of central Changping district,and the eastern parts of Mentougou and Fangshan districts.Among the 37 geological hazard events recorded in 2024,67.57％occurred within high-and relatively high-susceptibility zones,validating the predictive accuracy of the model.This study reveals the multi-factor coupling and complex response mechanism of"geological foundation-topographic manifestation-environmental triggering."The improved frequency ratio method effectively reduces the subjectivity in factor classification and the discontinuity inherent in the traditional method,significantly enhancing model discrimination capability.The results provide a scientific basis for geological disaster risk management in the mountainous areas of Beijing.High-susceptibility zones are concentrated around key ecological areas such as the Miyun reservoir and southern Huairou,where disaster prevention and mitigation efforts should be prioritized,providing theoretical guidance for targeted geological disaster prevention measures.
Inclined double-row piles have been widely applied in slope and foundation pit support projects,showing favorable engineering performance.However,their application in subgrade engineering is seldom reported,and design parameters remains difficult to determine.This study investigates the mechanical behavior of positive-negative battered double-row piles under varying row spacings in multi-layered soil foundations,aiming to identify optimal row spacing for subgrade engineering,which is crucial for disaster prevention and mitigation.Based on the test section of the Huizhou-Zhaoqing expressway in Guangdong Province,this study conducts numerical simulations using the finite element software ABAQUS.Results show that:(1)The bending moment and its peak in both front and rear battered piles increase with rising load and loading stages.The bending moment along the pile shaft initially increases and then decreases,with the peak positive bending moment occurring in the upper-middle section,making it susceptible to flexural failure.(2)Lateral displacement of both front and rear battered piles along the pile shaft initially increases and then decreases,with the maximum displacement also in the upper-middle section.(3)The bending moment and lateral displacement of rear positive-battered piles increase with larger row spacing,while those of front negative-battered piles decrease with increasing row spacing.(4)Peak bending moment of rear positive-battered piles exceeds those of front negative-battered piles;the sum of peak moments decreases with increasing row spacing,while the difference increases.For engineering practice,it is recommended that row spacing be 2-4 times the pile diameter.While increasing row spacing,the flexural stiffness of rear positive-battered piles should be enhanced to ensure foundation stability.
In response to the increasingly prominent issue of road surface collapses driven by high-intensity underground space development in major and medium-sized cities in China,this study proposes a scientifically robust susceptibility assessment model to analyze spatial distribution patterns and support safe urban planning and disaster prevention.The aim is to mitigate the threats posed by road collapses to urban public safety and infrastructure,ensuring the safety of residents' lives and property.Based on 38 road collapse incidents recorded in Hangzhou from 2008 to 2024,twelve evaluation indicators were selected to construct a localized susceptibility index system.Feature importance ranking and collinearity analysis were conducted to refine the indicators.To address the sample imbalance issue,a negative sample selection method based on grid cell size was adopted,and the synthetic minority oversampling technique(SMOTE)was applied to balance the positive and negative samples.On this basis,a random forest model was then used to compute a road collapse susceptibility index for Hangzhou.Finally,the natural breaks classification method is used to divide the study area into high,medium,and low susceptibility zones-completing the susceptibility evaluation of road collapses in the study area.The results indicate that road collapse susceptibility in Hangzhou exhibits a spatially decreasing pattern radiating outward from the central plains of Gongshu,Shangcheng,Binjiang,and Xihu districts.Specifically,high-susceptibility zones account for 12.36％(325.87 km2)of the area,medium-susceptibility zones for 30.45％(802.52 km2),and low-susceptibility zones for 57.19％(1,507.56 km2).This research reveals the spatial distribution patterns of road collapse susceptibility in Hangzhou and offers scientific guidance for the prediction and prevention of road collapse susceptibility in Hangzhou.
Under the background of frequent extreme rainfall, rainfall-induced gravelly soil landslides have become a major disaster type in the mountainous areas of Southwest China. To systematically reveal the deformation mechanism of landslides with different gravel contents under the combined action of rainfall and groundwater level, this study employs laboratory model tests. Four gravel content scenarios (10%, 20%, 30%, 40%) are simulated to analyze the variation laws of volumetric moisture content, pore water pressure, earth pressure, and deformation displacement. The study investigates the evolution patterns of landslides under different conditions and verifies the findings through field case comparisons. The results show that with the increase of gravel content, soil porosity and permeability coefficient increase, the peak values of volumetric water content and pore water pressure decrease significantly, earth pressure increases, and the overall sliding risk reduces. The earth pressure at different positions of the landslide shows different responses: the earth pressure at the rear and central zones first increases and then gradually stabilizes. Meanwhile, with the increase of gravel content, the failure mode of the landslide changes from a composite evolution mode of frontal traction and rearward thrust to a typical traction evolution mode. The conclusion of the model test is consistent with field cases, confirming that gravel content is a key parameter affecting the evolution path of landslides, which provides a reference for the early identification, stability evaluation, and treatment of gravelly soil landslides under high groundwater conditions.
