The upper reaches of the Yellow River in Sichuan Province are critical area for water conservation and ecological protection in China. However, they are experiencing a range of ecological and environmental challenges,...The upper reaches of the Yellow River in Sichuan Province are critical area for water conservation and ecological protection in China. However, they are experiencing a range of ecological and environmental challenges, including grassland desertification, wetland degradation, and soil erosion, all of which pose significant threats to the environmental sustainability and overall development of the Yellow River Basin. Urbanization can lead to irreversible damage to ecosystems. Therefore, understanding the relationship between urbanization and ecosystems is crucial for fostering sustainable development in the region. With land use and meteorological data in the upper reaches of the Yellow River in Sichuan Province in 2000-2020, and using InVEST model and standardized processing methods, we analyzed the spatiotemporal evolution characteristics of urbanization and four ecosystem services: water conservation, carbon storage, habitat quality, and soil retention. Additionally, we employed the GeoDa bivariate spatial autocorrelation analysis model to reveal the spatial correlations and interactions between urbanization and ecosystems. The results reveal a significant spatial mismatch between urbanization and ecosystem services in the upper Yellow River region of Sichuan Province. While the composite urbanization index decreased from 0.0075 to 0.0042 and remained concentrated in county centers, all ecosystem services showed improvement: water conservation increased from 17.38×10^(9) mm to 23.37×10^(9) mm, carbon storage rose from 936.60 Tg to 938.42 Tg, habitat quality improved from 0.875 to 0.879, and soil retention enhanced from 13.56×10^(8) t to 17.59×10^(8) t. However, these ecological gains were mainly driven by restoration in non-urban southern areas, creating a clear spatial disconnection from urban centers and leading to persistently weak and declining coordination between systems. This spatial decoupling underscores the inadequacy of the current urbanization model in promoting regional ecological synergy. We therefore recommend implementing differentiated zoning strategies: promoting compact development coupled with ecological restoration in county centers, strictly protecting core water conservation and carbon sequestration areas in the southern key ecological zones, and enhancing soilwater conservation and ecological restoration in the vulnerable northern belt, so as to establish an ecological security framework compatible with sustainable urbanization.展开更多
A large amount of loose debris materials were deposited on the slope of mountainous areas after the 2008 Ms 8.0 Wenchuan earthquake. During and after the earthquake, these loose debris deposits collapsed and slide int...A large amount of loose debris materials were deposited on the slope of mountainous areas after the 2008 Ms 8.0 Wenchuan earthquake. During and after the earthquake, these loose debris deposits collapsed and slide into valleys or rivers, changing river sediment supply condition and channel morphology. To investigate the mechanisms of granular flow and deposition, the dynamics of slope failure and sediment transportation in typical mountainous rivers of different intersection angles were analyzed with a coupling model of Computational Fluid Dynamics and Discrete Element Method(CFD-DEM). The numerical results show that the change of intersection angle between the granular flow flume and the river channel can affect the deposit geometry and the fluid flow field significantly. As the intersection angle increases, the granular velocity perpendicular to the river channel increases, while the granular velocity parallel to the river channel decreases gradually. Compared to the test of dry granular flow, the CFD-DEM coupling tests show much higher granular velocity and larger volume of sediments entrained in the river. Due to the river flow, particles located at the edge of the deposition will move downstream gradually and the main section of sediments deposition moves from the center to the edge of the river channel. As a result, sediment supply in the downstream river will distribute unevenly. Under the erosion of fluid flow, the proportion of fine particles increases, while the proportion of coarse particles decreases gradually in the sediment deposition. The build-up of accumulated sediment mass will cause a significant increase in water level in the river channel, thus creating serious flooding hazard in mountainous rivers.展开更多
The cumulative effect of cascade hydropower stations on river ecological environment has been widely concerned because of the significant streamflow hydrology change induced by dam constructions. The characteristics o...The cumulative effect of cascade hydropower stations on river ecological environment has been widely concerned because of the significant streamflow hydrology change induced by dam constructions. The characteristics of the change in the lower reaches of the Jinsha River, China are analyzed based on long-term(1952–2015) hydrological and sedimentological data. The averaging coefficient, reservoir regulation coefficient(RRC), incoming sediment coefficient(ISC), and sediment transport modulus(STM), which reflect the variation of streamflow and sediment regimes, are defined and calculated. The results show that the construction and regulation of reservoirs reduces flow in flood season, increases flow in dry season, significantly altering the monthly discharge regimes. These alterations also led directly to changes in the timing of extreme flows at Pingshan Station. The monthly flow records at the basin outlet are reconstructed using stepwise regression, to reduce reservoir impacts. Comparisons of observed and reconstructed monthly flows demonstrate that the previous studies overestimated the cumulative effects of cascade reservoirs on flow processes. Furthermore, this study clearly illustrates that the reduction in sediment trapping and sediment transportation capacity together lead to the sharp reduction in annual sediment yield at the Pingshan Station. The earlier constructed reservoirs have more obvious effects on the ISC and STM than the more recent reservoirs and the effect of sediment trapping is related to reservoir location, on the main stream versus tributaries.展开更多
For high-steep slopes in hydropower engineering, damage can be induced or accumulated due to a seriesof human or natural activities, including excavation, dam construction, earthquake, rainstorm, rapid riseor drop of ...For high-steep slopes in hydropower engineering, damage can be induced or accumulated due to a seriesof human or natural activities, including excavation, dam construction, earthquake, rainstorm, rapid riseor drop of water level in the service lifetime of slopes. According to the concept that the progressivedamage （microseismicity） of rock slope is the essence of the precursor of slope instability, a microseismicmonitoring system for high-steep rock slopes is established. Positioning accuracy of the monitoringsystem is tested by fixed-position blasting method. Based on waveform and cluster analyses of microseismicevents recorded during test, the tempo-spatial distribution of microseismic events is analyzed.The deformation zone in the deep rock masses induced by the microseismic events is preliminarilydelimited. Based on the physical information measured by in situ microseismic monitoring, an evaluationmethod for the dynamic stability of rock slopes is proposed and preliminarily implemented bycombining microseismic monitoring and numerical modeling. Based on the rock mass damage modelobtained by back analysis of microseismic information, the rock mass elements within the microseismicdamage zone are automatically searched by finite element program. Then the stiffness and strengthreductions are performed on these damaged elements accordingly. Attempts are made to establish thecorrelation between microseismic event, strength deterioration and slope dynamic instability, so as toquantitatively evaluate the dynamic stability of slope. The case studies about two practical slopes indicatethat the proposed method can reflect the factor of safety of rock slope more objectively. Numericalanalysis can help to understand the characteristics and modes of the monitored microseismic events inrock slopes. Microseismic monitoring data and simulation results can be used to mutually modify thesensitive rock parameters and calibrate the model. Combination of microseismic monitoring and numericalsimulation provides a more objective basis for the numerical model and parameters and a solidmechanical foundation for the microseismic monitoring.展开更多
Increased urbanisation,economic growth,and long-term climate variability have made both the UK and China more susceptible to urban and river flooding,putting people and property at increased risk.This paper presents a...Increased urbanisation,economic growth,and long-term climate variability have made both the UK and China more susceptible to urban and river flooding,putting people and property at increased risk.This paper presents a review of the current flooding challenges that are affecting the UK and China and the actions that each country is undertaking to tackle these problems.Particular emphases in this paper are laid on(1)learning from previous flooding events in the UK and China,and(2)which management methodologies are commonly used to reduce flood risk.The paper concludes with a strategic research plan suggested by the authors,together with proposed ways to overcome identified knowledge gaps in flood management.Recommendations briefly comprise the engagement of all stakeholders to ensure a proactive approach to land use planning,early warning systems,and water-sensitive urban design or redesign through more effective policy,multi-level flood models,and data driven models of water quantity and quality.展开更多
The Yellow River Basin in Sichuan Province(YRS)is undergoing severe soil erosion and exacerbated ecological vulnerability,which collectively pose formidable challenges for regional water conservation(WC)and sustainabl...The Yellow River Basin in Sichuan Province(YRS)is undergoing severe soil erosion and exacerbated ecological vulnerability,which collectively pose formidable challenges for regional water conservation(WC)and sustainable development.While effectively enhancing WC necessitates a comprehensive understanding of its driving factors and corresponding intervention strategies,existing studies have largely neglected the spatiotemporal heterogeneity of both natural and socio-economic drivers.Therefore,this study explored the spatiotemporal heterogeneity of WC drivers in YRS using multi-scale geographically weighted regression(MGWR)and geographically and temporally weighted regression(GTWR)models from an eco-hydrological perspective.We discovered that downstream regions,which are more developed,achieved significantly better WC than upstream regions.The results also demonstrated that the influence of temperature and wind speed is consistently dominant and temporally stable due to climate stability,while the influence of vegetation shifted from negative to positive around 2010,likely indicating greater benefits from understory vegetation.Economic growth positively impacted WC in upstream regions but had a negative effect in the more developed downstream regions.These findings highlight the importance of targeted water conservation strategies,including locally appropriate revegetation,optimization of agricultural and economic structures,and the establishment of eco-compensation mechanisms for ecological conservation and sustainable development.展开更多
Surrounding rock deterioration and large deformation have always been a significant difficulty in designing and constructing tunnels in soft rock.The key lies in real-time perception and quantitative assessment of the...Surrounding rock deterioration and large deformation have always been a significant difficulty in designing and constructing tunnels in soft rock.The key lies in real-time perception and quantitative assessment of the damaged area around the tunnel.An in situ microseismic(MS)monitoring system is established in the plateau soft tock tunnel.This technique facilitates spatiotemporal monitoring of the rock mass's fracturing expansion and squeezing deformation,which agree well with field convergence deformation results.The formation mechanisms of progressive failure evolution of soft rock tunnels were discussed and analyzed with MS data and numerical results.The results demonstrate that:(1)Localized stress concentration and layered rock result in significant asymmetry in micro-fractures propagation in the tunnel radial section.As excavation continues,the fracture extension area extends into the deep surrounding rockmass on the east side affected by the weak bedding;(2)Tunnel excavation and long-term deformation can induce tensile shear action on the rock mass,vertical tension fractures(account for 45%)exist in deep rockmass,which play a crucial role in controlling the macroscopic failure of surrounding rock;and(3)Based on the radiated MS energy,a three-dimensional model was created to visualize the damage zone of the tunnel surrounding rock.The model depicted varying degrees of damage,and three high damage zones were identified.Generally,the depth of high damage zone ranged from 4 m to 12 m.This study may be a valuable reference for the warning and controlling of large deformations in similar projects.展开更多
Presently concepts and methods related to water resources conservation of mountain rivers are seriously insufficient,and its level is far from being adaptable to the development of a harmonious society.As mountain eco...Presently concepts and methods related to water resources conservation of mountain rivers are seriously insufficient,and its level is far from being adaptable to the development of a harmonious society.As mountain ecosystems play a key role in water resources conservation of mountain rivers,and the characteristics of mountain ecosystems and hydrologic features of mountain river follow strong temporal and spatial distribution,partition theory can be applied to the water resources conservation of mountain river.This theory observes the following partition principles:regional relativity,spatial continuity,integralcounty,meeting management needs,hierarchical principle,and comparability principle.And it lays equal emphasis on both water resources conservation and environmental protection,on both water quality conservation and water quantity protection,on the combination of water features,water cycle and water pollution.In the partition methods,index method and map superposition method will be applied in region partition.The example of region partition of water resources conservation in the upper reaches of the Yangtze River shows that the partition theory is practicable in water resources conservation of mountain rivers,and it provides a platform for future study in water resources conservation.展开更多
With the increasing of extreme rainfall frequency, landslides accompanied by mudslides often lead to serious casualties and property damage. On 3rd July 2021, a debris flow occurred in Izu Mountain area, Shizuoka Coun...With the increasing of extreme rainfall frequency, landslides accompanied by mudslides often lead to serious casualties and property damage. On 3rd July 2021, a debris flow occurred in Izu Mountain area, Shizuoka County, Japan, and then resulted in 26 deaths and 131 houses destroyed, where houses were mainly built along the banks of the creek. In order to analyse the landslide state and distribution, a two-dimensional debris flow dynamic model(Massflow) was selected to simulate the process of the landslide-generated debris flow. When the model results are considered together with remote sensing images, the volume distribution of the unstable landslide is also able to be determined. The results show that(1) the affected areas are mainly concentrated at the outfall of the gully and on both sides of the streets.(2) The pore pressure ratio is an important factor affecting the damage range of this debris flow.(3) The increase of the pore pressure ratio in the landslide make the movement distance of debris flow increase significantly.展开更多
On 10th Oct.and 3rd Nov.2018,two successive landslides occurred in the Jinsha River catchment at Baige Village,Tibet Autonomous Region,China.The landslides blocked the major river and formed the barrier lake,which fin...On 10th Oct.and 3rd Nov.2018,two successive landslides occurred in the Jinsha River catchment at Baige Village,Tibet Autonomous Region,China.The landslides blocked the major river and formed the barrier lake,which finally caused the huge flood disaster loss.The hillslope at Baige landslide site has been still deforming after the 2018 slidings,which is likely to fail and block the Jinsha River again in the future.Therefore the investigation of 2018 flood disaster at the Baige landslide is of a great significance to provide a classic case for flood assessment and early warning for the future disaster.The detailed survey revealed that the outstanding inundations induced bank collapse disasters upstream the Baige landslide dams,and the field investigations and hydrological simulation suggested that the downstream of the Baige landslide were seriously flooded due to the two periods of the outburst floods.On these bases,the early warning process of potential outburst floods at the Baige landslide was advised,which contains four stages:Outburst Flood Simulating Stage,Outburst Flood Forecasting Stage,Emergency Plan and Emergency Evacuation Stage.The study offers a conceptual model for the mitigation of landslides and flood disasters in the high-relief mountain-ous region in Tibet.展开更多
Rainwater runoff that does not infiltrate the soil during heavy rainfall may increase slope instability. The effect of runoff is usually neglected in conventional rainfall-induced slope failure analysis to simplify th...Rainwater runoff that does not infiltrate the soil during heavy rainfall may increase slope instability. The effect of runoff is usually neglected in conventional rainfall-induced slope failure analysis to simplify the model. To analyze the effect of runoff on slope stability, this study simultaneously simulated the effects of surface runoff and rainfall infiltration on bank slopes in the Three Gorges Reservoir Area. A shallow slope failure method that can be used to analyze runoff was proposed based on the modified Green-Ampt model, the simplified Saint-Venant model, and the infinite slope model. In this model, the modified Green–Ampt model was used to estimate the rainfall infiltration capacity and the wetting front depth. The eight-flow(D8) method and the simplified Saint-Venant model were selected to estimate the distribution of runoff. By considering the wetting front depth as the slip surface depth, the factor of safety of the slope could be determined using the infinite slope stability model. A comparison of the different models reveals that runoff can escalate the instability of certain slopes, causing stable slopes to become unstable. Comparison of the unstable areas obtained from the simulation with the actual landslide sites shows that the model proposed in this study can successfully predict landslides at these sites. The slope instability assessment model proposed in this study offers an alternative approach for estimating high-risk areas in large mountainous regions.展开更多
In recent years,regional floods and typhoons have occurred in the Yangtze Estuary.Changing dynamic conditions and dramatic reduction of sediment discharge in the basin are affecting the dynamic equilibrium pattern of ...In recent years,regional floods and typhoons have occurred in the Yangtze Estuary.Changing dynamic conditions and dramatic reduction of sediment discharge in the basin are affecting the dynamic equilibrium pattern of the Yangtze Estuary.Based on the field measurement data and theoretical derivation,this paper analyzed the changing process of runoff-sediment discharge into the sea after the operation of the Three Gorges Project(TGP),and the tidal dynamics and sediment variation characteristics of the Yangtze Estuary.The erosion of South Branch mainly occurs in the channel below-10 m contour,and the riverbed volume below contours 0 m and-10 m has a good correlation with the sediment discharge of Datong Station in the previous year.On this basis,the ratio of the horizontal distance from the starting point to the section centroid below the average water level(B_c)and the water depth at the section centroid(H_c)was proposed to describe the change of the section shape.The relationships between the water-diverting ratio,the sediment-diverting ratio and the water-diverting angle,the conditions of runoff and sediment discharge from the upper reach and the characteristics of the riverway section were established,and the theoretical calculation equations of the water-diverting ratio,the sediment-diverting ratio and the diverting angle of each bifurcation were also established.展开更多
Flexible net barriers are a new type of effective mitigation measure against debris flows in valleys and can affect the kinematic energy and mass of debris flows. Here, ten flume tests were performed to study the dyna...Flexible net barriers are a new type of effective mitigation measure against debris flows in valleys and can affect the kinematic energy and mass of debris flows. Here, ten flume tests were performed to study the dynamic behaviours of debris flows with differences in volumes, concentrations(solid volume fraction), and travel distances after interception by a uniform flexible net barrier. A high-speed camera was used to monitor the whole test process, and their dynamic behaviours were recorded. A preliminary computational framework on energy conversion is proposed according to the deposition mechanisms and outflow of debris flow under the effects of the flexible net barrier. The experimental results show that the dynamic interaction process between a debris flow and the flexible net barrier can be divided into two stages:(a) the two-phase impact of the leading edge of the debris flow with the net and(b) collision and friction between the body of the debris flow and intercepted debris material. The approach velocity of a debris flow decreases sharply(a maximum of 63%) after the interception by the net barrier, and the mass ratio of the debris material being intercepted and the kinetic energy ratio of the debris material being absorbed by the net barrier are close due to the limited interception efficiency of the flexible net barrier, which is believed to be related to the flexibility. The energy ratio of outflow is relative small despite the large permeability of the flexible net barrier.展开更多
Accurate dynamic modeling of landslides could help understand the movement mechanisms and guide disaster mitigation and prevention.Discontinuous deformation analysis(DDA)is an effective approach for investigating land...Accurate dynamic modeling of landslides could help understand the movement mechanisms and guide disaster mitigation and prevention.Discontinuous deformation analysis(DDA)is an effective approach for investigating landslides.However,DDA fails to accurately capture the degradation in shear strength of rock joints commonly observed in high-speed landslides.In this study,DDA is modified by incorporating simplified joint shear strength degradation.Based on the modified DDA,the kinematics of the Baige landslide that occurred along the Jinsha River in China on 10 October 2018 are reproduced.The violent starting velocity of the landslide is considered explicitly.Three cases with different violent starting velocities are investigated to show their effect on the landslide movement process.Subsequently,the landslide movement process and the final accumulation characteristics are analyzed from multiple perspectives.The results show that the violent starting velocity affects the landslide motion characteristics,which is found to be about 4 m/s in the Baige landslide.The movement process of the Baige landslide involves four stages:initiation,high-speed sliding,impact-climbing,low-speed motion and accumulation.The accumulation states of sliding masses in different zones are different,which essentially corresponds to reality.The research results suggest that the modified DDA is applicable to similar high-level rock landslides.展开更多
Elevation plays a crucial factor in the distribution of plants,as environmental conditions become increasingly harsh at higher elevations.Previous studies have mainly focused on the effects of large-scale elevational ...Elevation plays a crucial factor in the distribution of plants,as environmental conditions become increasingly harsh at higher elevations.Previous studies have mainly focused on the effects of large-scale elevational gradients on plants,with little attention on the impact of smaller-scale gradients.In this study we used 14 microsatellite loci to survey the genetic structure of 332 Juniperus squamata plants along elevation gradient from two sites in the Hengduan Mountains.We found that the genetic structure(single,clonal,mosaic)of J.squamata shrubs is affected by differences in elevational gradients of only 150 m.Shrubs in the mid-elevation plots rarely have a clonal or mosaic structure compared to shrubs in lower-or higher-elevation plots.Human activity can significantly affect genetic structure,as well as reproductive strategy and genetic diversity.Sub-populations at mid-elevations had the highest yield of seed cones,lower levels of asexual reproduction and higher levels of genetic diversity.This may be due to the trade-off between elevational stress and anthropogenic disturbance at mid-elevation since there is greater elevational stress at higher-elevations and greater intensity of anthropogenic disturbance at lower-elevations.Our findings provide new insights into the finer scale genetic structure of alpine shrubs,which may improve the conservation and management of shrublands,a major vegetation type on the Hengduan Mountains and the Qinghai-Tibet Plateau.展开更多
Exploring dynamic mechanical responses and failure behaviors of hot dry rock(HDR)is significant for geothermal exploitation and stability assessment.In this study,via the split Hopkinson pressure bar(SHPB)system,a ser...Exploring dynamic mechanical responses and failure behaviors of hot dry rock(HDR)is significant for geothermal exploitation and stability assessment.In this study,via the split Hopkinson pressure bar(SHPB)system,a series of dynamic compression tests were conducted on granite treated by cyclic thermal shocks at different temperatures.We analyzed the effects of cyclic thermal shock on the thermal-related physical and dynamic mechanical behaviors of granite.Specifically,the P-wave velocity,dynamic strength,and elastic modulus of the tested granite decrease with increasing temperature and cycle number,while porosity and peak strain increase.The degradation law of dynamic mechanical properties could be described by a cubic polynomial.Cyclic thermal shock promotes shear cracks propagation,causing dynamic failure mode of granite to transition from splitting to tensile-shear composite failure,accompanied by surface spalling and debris splashing.Moreover,the thermal shock damage evolution and coupled failure mechanism of tested granite are discussed.The evolution of thermal shock damage with thermal shock cycle numbers shows an obvious S-shaped surface,featured by an exponential correlation with dynamic mechanical parameters.In addition,with increasing thermal shock temperature and cycles,granite mineral species barely change,but the length and width of thermal cracks increase significantly.The non-uniform expansion of minerals,thermal shock-induced cracking,and water-rock interaction are primary factors for deteriorating dynamic mechanical properties of granite under cyclic thermal shock.展开更多
Rainstorm-induced flood hazards in mountainous areas often result in complex cascading effects by interacting with environmental and human systems.However,traditional studies typically categorize them simply as clearw...Rainstorm-induced flood hazards in mountainous areas often result in complex cascading effects by interacting with environmental and human systems.However,traditional studies typically categorize them simply as clearwater floods or debris floods/flows,overlooking their evolutionary characteristics and compound impacts.This study presents a novel classification-based approach to investigate the formation and destructive mechanisms of a catastrophic composite disaster of flash flood and debris flow in the Dayao Gully(DYG)catchment in Hanyuan County,Sichuan Province,China.The event resulted in 14 fatalities,25 missing persons,and extensive infrastructure damage.Through comprehensive field investigations and multi-method analysis,three distinct disaster zones were identified with different magnitudes and impacts:(1)a clearwater flood disaster region with minimal geomorphological changes under a 5-year return period rainfall;(2)a debris flood disaster region triggered by a 30-year return period rainfall,leading to intense sediment transport with a total deposit volume of 52,511 m^(3);and(3)a sediment-induced flood disaster region characterized by significant riverbed aggradation and infrastructure destruction due to sediment-induced blockage effects.The results reveal that the cascading characteristics of this composite disaster were primarily driven by intense rainfall,enhanced sediment transport motivated by supracritical shear stress,and interactions with human infrastructure(e.g.,bridges and buildings).This classification-based approach provides a quantitative assessment of spatial characteristics of cascading flood disasters,offering new insights into their evolutionary characteristics and highlighting the necessity for targeted disaster mitigation strategies in sedimentprone mountainous regions.展开更多
New energy vehicles are distinguished by their environmentally friendly characteristics;however,their sales remain low compared with those of fossil fuel vehicles.This study identifies the key factors influencing cons...New energy vehicles are distinguished by their environmentally friendly characteristics;however,their sales remain low compared with those of fossil fuel vehicles.This study identifies the key factors influencing consumer purchases of new energy vehicles with the aim of increasing sales and promoting the development of the new energy vehicle industry.Machine learning(ML)techniques were employed to analyze more than 26000 consumer reviews of new energy vehicles and identify the factors influencing their purchasing decisions.Subsequently,a hybrid simulation model was constructed using the complex adaptive system framework.The model combines the strengths of ML,multi-agent modeling,and system dynamics modeling,thereby enhancing its capacity to identify key factors.The model comprises two categories of manufacturers:producers of new energy vehicles and producers of fossil fuel vehicles.Dynamic simulations were conducted using the AnyLogic simulation platform.The findings indicated a negative correlation between consumer income and demand for new energy vehicles.Conversely,expansions in the interior space of new energy vehicles and favorable consumer perceptions of their environmental benefits have contributed to increased demand for these vehicles.Therefore,rather than exclusively focusing on price advantages,it would be more beneficial to prioritize expanding new energy vehicles’interior space and disseminating information about their environmental benefits to consumers.It seems reasonable to posit that these strategies would increase consumer willingness to purchase new energy vehicles in the long term.展开更多
Landslide dam failures can cause significant damage to both society and ecosystems.Predicting the failure of these dams in advance enables early preventive measures,thereby minimizing potential harm.This paper aims to...Landslide dam failures can cause significant damage to both society and ecosystems.Predicting the failure of these dams in advance enables early preventive measures,thereby minimizing potential harm.This paper aims to propose a fast and accurate model for predicting the longevity of landslide dams while also addressing the issue of missing data.Given the wide variation in the survival times of landslide dams—from mere minutes to several thousand years—predicting their longevity presents a considerable challenge.The study develops predictive models by considering key factors such as dam geometry,hydrodynamic conditions,materials,and triggering parameters.A dataset of 1045 landslide dam cases is analyzed,categorizing their longevity into three distinct groups:C1(<1 month),C2(1 month to 1 year),and C3(>1 year).Multiple imputation and knearest neighbor algorithms are used to handle missing data on geometric size,hydrodynamic conditions,materials,and triggers.Based on the imputed data,two predictive models are developed:a classification model for dam longevity categories and a regression model for precise longevity predictions.The classification model achieves an accuracy of 88.38%while the regression model outperforms existing models with an R^(2) value of 0.966.Two real-life landslide dam cases are used to validate the models,which show correct classification and small prediction errors.The longevity of landslide dams is jointly influenced by factors such as geometric size,hydrodynamic conditions,materials,and triggering events.Among these,geometric size has the greatest impact,followed by hydrodynamic conditions,materials,and triggers,as confirmed by variable importance in the model development.展开更多
To elucidate the influence of confining pressure on microcrack evolution and macroscopic failure mechanisms in granite,a multi-perspective approach was adopted.This approach combined triaxial compression tests,acousti...To elucidate the influence of confining pressure on microcrack evolution and macroscopic failure mechanisms in granite,a multi-perspective approach was adopted.This approach combined triaxial compression tests,acoustic emission(AE)monitoring,and PFC simulations.The results show that:1)Confining pressure exhibits a pronounced linear correlation with both yield strength and compressive strength.The enhancement of confining pressure significantly improves the deformability of granite and promotes a progressive shift in failure mechanism from brittle rupture to ductile deformation;2)Increasing confining pressure elevates the stress threshold for microcrack initiation and suppresses crack propagation.As a result,the proportion of shear cracks increases(based on AE analysis)from 18.71%to 61.2%,marking a transition in the dominant failure mode from tensile to shear;3)Confining pressure facilitates the development of grain boundary shear cracks(GBSCs),establishing the primary damage pathways.In addition,local stress concentrations under high confinement conditions trigger intragranular cracking.This highlights the regulatory effect of confining pressure on microcrack evolution.展开更多
基金supported by the funding provided by the State Key Laboratory of Hydraulics and Mountain River Engineering (SKHL2210)National Natural Science Foundation of China (42171304)the Sichuan Science and Technology Program (2023YFS0380,2023YFS0377,2023NSFSC1989)。
文摘The upper reaches of the Yellow River in Sichuan Province are critical area for water conservation and ecological protection in China. However, they are experiencing a range of ecological and environmental challenges, including grassland desertification, wetland degradation, and soil erosion, all of which pose significant threats to the environmental sustainability and overall development of the Yellow River Basin. Urbanization can lead to irreversible damage to ecosystems. Therefore, understanding the relationship between urbanization and ecosystems is crucial for fostering sustainable development in the region. With land use and meteorological data in the upper reaches of the Yellow River in Sichuan Province in 2000-2020, and using InVEST model and standardized processing methods, we analyzed the spatiotemporal evolution characteristics of urbanization and four ecosystem services: water conservation, carbon storage, habitat quality, and soil retention. Additionally, we employed the GeoDa bivariate spatial autocorrelation analysis model to reveal the spatial correlations and interactions between urbanization and ecosystems. The results reveal a significant spatial mismatch between urbanization and ecosystem services in the upper Yellow River region of Sichuan Province. While the composite urbanization index decreased from 0.0075 to 0.0042 and remained concentrated in county centers, all ecosystem services showed improvement: water conservation increased from 17.38×10^(9) mm to 23.37×10^(9) mm, carbon storage rose from 936.60 Tg to 938.42 Tg, habitat quality improved from 0.875 to 0.879, and soil retention enhanced from 13.56×10^(8) t to 17.59×10^(8) t. However, these ecological gains were mainly driven by restoration in non-urban southern areas, creating a clear spatial disconnection from urban centers and leading to persistently weak and declining coordination between systems. This spatial decoupling underscores the inadequacy of the current urbanization model in promoting regional ecological synergy. We therefore recommend implementing differentiated zoning strategies: promoting compact development coupled with ecological restoration in county centers, strictly protecting core water conservation and carbon sequestration areas in the southern key ecological zones, and enhancing soilwater conservation and ecological restoration in the vulnerable northern belt, so as to establish an ecological security framework compatible with sustainable urbanization.
基金supported by the National Natural Science Foundation of China (51579163 and 51639007)the National Key R&D Program of China (2017YFC1502504 and 2016YFC0402304)
文摘A large amount of loose debris materials were deposited on the slope of mountainous areas after the 2008 Ms 8.0 Wenchuan earthquake. During and after the earthquake, these loose debris deposits collapsed and slide into valleys or rivers, changing river sediment supply condition and channel morphology. To investigate the mechanisms of granular flow and deposition, the dynamics of slope failure and sediment transportation in typical mountainous rivers of different intersection angles were analyzed with a coupling model of Computational Fluid Dynamics and Discrete Element Method(CFD-DEM). The numerical results show that the change of intersection angle between the granular flow flume and the river channel can affect the deposit geometry and the fluid flow field significantly. As the intersection angle increases, the granular velocity perpendicular to the river channel increases, while the granular velocity parallel to the river channel decreases gradually. Compared to the test of dry granular flow, the CFD-DEM coupling tests show much higher granular velocity and larger volume of sediments entrained in the river. Due to the river flow, particles located at the edge of the deposition will move downstream gradually and the main section of sediments deposition moves from the center to the edge of the river channel. As a result, sediment supply in the downstream river will distribute unevenly. Under the erosion of fluid flow, the proportion of fine particles increases, while the proportion of coarse particles decreases gradually in the sediment deposition. The build-up of accumulated sediment mass will cause a significant increase in water level in the river channel, thus creating serious flooding hazard in mountainous rivers.
基金financially supported by the National 973 Program of China (2015CB452701)the National Natural Science Foundation of China (Grant No. 51579161)
文摘The cumulative effect of cascade hydropower stations on river ecological environment has been widely concerned because of the significant streamflow hydrology change induced by dam constructions. The characteristics of the change in the lower reaches of the Jinsha River, China are analyzed based on long-term(1952–2015) hydrological and sedimentological data. The averaging coefficient, reservoir regulation coefficient(RRC), incoming sediment coefficient(ISC), and sediment transport modulus(STM), which reflect the variation of streamflow and sediment regimes, are defined and calculated. The results show that the construction and regulation of reservoirs reduces flow in flood season, increases flow in dry season, significantly altering the monthly discharge regimes. These alterations also led directly to changes in the timing of extreme flows at Pingshan Station. The monthly flow records at the basin outlet are reconstructed using stepwise regression, to reduce reservoir impacts. Comparisons of observed and reconstructed monthly flows demonstrate that the previous studies overestimated the cumulative effects of cascade reservoirs on flow processes. Furthermore, this study clearly illustrates that the reduction in sediment trapping and sediment transportation capacity together lead to the sharp reduction in annual sediment yield at the Pingshan Station. The earlier constructed reservoirs have more obvious effects on the ISC and STM than the more recent reservoirs and the effect of sediment trapping is related to reservoir location, on the main stream versus tributaries.
基金supported by grants from the National Basic Research Program of China (Grant Nos. 2011CB013503, 2014CB047103)the National Natural Science Foundation of China (Grant Nos. 51279024, 51209127)
文摘For high-steep slopes in hydropower engineering, damage can be induced or accumulated due to a seriesof human or natural activities, including excavation, dam construction, earthquake, rainstorm, rapid riseor drop of water level in the service lifetime of slopes. According to the concept that the progressivedamage （microseismicity） of rock slope is the essence of the precursor of slope instability, a microseismicmonitoring system for high-steep rock slopes is established. Positioning accuracy of the monitoringsystem is tested by fixed-position blasting method. Based on waveform and cluster analyses of microseismicevents recorded during test, the tempo-spatial distribution of microseismic events is analyzed.The deformation zone in the deep rock masses induced by the microseismic events is preliminarilydelimited. Based on the physical information measured by in situ microseismic monitoring, an evaluationmethod for the dynamic stability of rock slopes is proposed and preliminarily implemented bycombining microseismic monitoring and numerical modeling. Based on the rock mass damage modelobtained by back analysis of microseismic information, the rock mass elements within the microseismicdamage zone are automatically searched by finite element program. Then the stiffness and strengthreductions are performed on these damaged elements accordingly. Attempts are made to establish thecorrelation between microseismic event, strength deterioration and slope dynamic instability, so as toquantitatively evaluate the dynamic stability of slope. The case studies about two practical slopes indicatethat the proposed method can reflect the factor of safety of rock slope more objectively. Numericalanalysis can help to understand the characteristics and modes of the monitored microseismic events inrock slopes. Microseismic monitoring data and simulation results can be used to mutually modify thesensitive rock parameters and calibrate the model. Combination of microseismic monitoring and numericalsimulation provides a more objective basis for the numerical model and parameters and a solidmechanical foundation for the microseismic monitoring.
基金supported by the National Key Research and Development Program of China(Grant No.2016YFE0122500)the Researcher Links Fund,British Council(Grant No.227109770)+1 种基金the National Natural Science Foundation of China(Grants No.5151101425 and 51579166)the Open Research Fund from the State Key Laboratory of Hydraulics and Mountain River Engineering,Sichuan University(Grants No.SKHL1601 and SKHL1602)
文摘Increased urbanisation,economic growth,and long-term climate variability have made both the UK and China more susceptible to urban and river flooding,putting people and property at increased risk.This paper presents a review of the current flooding challenges that are affecting the UK and China and the actions that each country is undertaking to tackle these problems.Particular emphases in this paper are laid on(1)learning from previous flooding events in the UK and China,and(2)which management methodologies are commonly used to reduce flood risk.The paper concludes with a strategic research plan suggested by the authors,together with proposed ways to overcome identified knowledge gaps in flood management.Recommendations briefly comprise the engagement of all stakeholders to ensure a proactive approach to land use planning,early warning systems,and water-sensitive urban design or redesign through more effective policy,multi-level flood models,and data driven models of water quantity and quality.
基金supported by the funding provided by the State Key Laboratory of Hydraulics and Mountain River Engineering(SKHL2210)National Natural Science Foundation of China(42171304)+1 种基金the Sichuan Science and Technology Program(2023YFS0380)Natural Science Foundation of Jiangsu Province of China(BK20242018)。
文摘The Yellow River Basin in Sichuan Province(YRS)is undergoing severe soil erosion and exacerbated ecological vulnerability,which collectively pose formidable challenges for regional water conservation(WC)and sustainable development.While effectively enhancing WC necessitates a comprehensive understanding of its driving factors and corresponding intervention strategies,existing studies have largely neglected the spatiotemporal heterogeneity of both natural and socio-economic drivers.Therefore,this study explored the spatiotemporal heterogeneity of WC drivers in YRS using multi-scale geographically weighted regression(MGWR)and geographically and temporally weighted regression(GTWR)models from an eco-hydrological perspective.We discovered that downstream regions,which are more developed,achieved significantly better WC than upstream regions.The results also demonstrated that the influence of temperature and wind speed is consistently dominant and temporally stable due to climate stability,while the influence of vegetation shifted from negative to positive around 2010,likely indicating greater benefits from understory vegetation.Economic growth positively impacted WC in upstream regions but had a negative effect in the more developed downstream regions.These findings highlight the importance of targeted water conservation strategies,including locally appropriate revegetation,optimization of agricultural and economic structures,and the establishment of eco-compensation mechanisms for ecological conservation and sustainable development.
基金the funding support from the National Natural Science Foundation of China(Grant Nos.U23A2060,42177143 and 42277461).
文摘Surrounding rock deterioration and large deformation have always been a significant difficulty in designing and constructing tunnels in soft rock.The key lies in real-time perception and quantitative assessment of the damaged area around the tunnel.An in situ microseismic(MS)monitoring system is established in the plateau soft tock tunnel.This technique facilitates spatiotemporal monitoring of the rock mass's fracturing expansion and squeezing deformation,which agree well with field convergence deformation results.The formation mechanisms of progressive failure evolution of soft rock tunnels were discussed and analyzed with MS data and numerical results.The results demonstrate that:(1)Localized stress concentration and layered rock result in significant asymmetry in micro-fractures propagation in the tunnel radial section.As excavation continues,the fracture extension area extends into the deep surrounding rockmass on the east side affected by the weak bedding;(2)Tunnel excavation and long-term deformation can induce tensile shear action on the rock mass,vertical tension fractures(account for 45%)exist in deep rockmass,which play a crucial role in controlling the macroscopic failure of surrounding rock;and(3)Based on the radiated MS energy,a three-dimensional model was created to visualize the damage zone of the tunnel surrounding rock.The model depicted varying degrees of damage,and three high damage zones were identified.Generally,the depth of high damage zone ranged from 4 m to 12 m.This study may be a valuable reference for the warning and controlling of large deformations in similar projects.
基金supported by National Natural Science Foundation of China(Grant No.40730634)State Key Laboratory of Geohazard Prevention and Geoenvironment Protection Project(Grant No.SKLGP2009z006)
文摘Presently concepts and methods related to water resources conservation of mountain rivers are seriously insufficient,and its level is far from being adaptable to the development of a harmonious society.As mountain ecosystems play a key role in water resources conservation of mountain rivers,and the characteristics of mountain ecosystems and hydrologic features of mountain river follow strong temporal and spatial distribution,partition theory can be applied to the water resources conservation of mountain river.This theory observes the following partition principles:regional relativity,spatial continuity,integralcounty,meeting management needs,hierarchical principle,and comparability principle.And it lays equal emphasis on both water resources conservation and environmental protection,on both water quality conservation and water quantity protection,on the combination of water features,water cycle and water pollution.In the partition methods,index method and map superposition method will be applied in region partition.The example of region partition of water resources conservation in the upper reaches of the Yangtze River shows that the partition theory is practicable in water resources conservation of mountain rivers,and it provides a platform for future study in water resources conservation.
基金supported by the National Key Research and Development of China(No.2019YFC1510603)National Natural Science Foundation of China(No.51639007)。
文摘With the increasing of extreme rainfall frequency, landslides accompanied by mudslides often lead to serious casualties and property damage. On 3rd July 2021, a debris flow occurred in Izu Mountain area, Shizuoka County, Japan, and then resulted in 26 deaths and 131 houses destroyed, where houses were mainly built along the banks of the creek. In order to analyse the landslide state and distribution, a two-dimensional debris flow dynamic model(Massflow) was selected to simulate the process of the landslide-generated debris flow. When the model results are considered together with remote sensing images, the volume distribution of the unstable landslide is also able to be determined. The results show that(1) the affected areas are mainly concentrated at the outfall of the gully and on both sides of the streets.(2) The pore pressure ratio is an important factor affecting the damage range of this debris flow.(3) The increase of the pore pressure ratio in the landslide make the movement distance of debris flow increase significantly.
基金The Second Tibetan Plateau Scientific Expedition and Research Program,No.2019QZKK0905National Key R&D Program of China,No.2018 YFC15050004National Natural Science Foundation Projects,No.42007248。
文摘On 10th Oct.and 3rd Nov.2018,two successive landslides occurred in the Jinsha River catchment at Baige Village,Tibet Autonomous Region,China.The landslides blocked the major river and formed the barrier lake,which finally caused the huge flood disaster loss.The hillslope at Baige landslide site has been still deforming after the 2018 slidings,which is likely to fail and block the Jinsha River again in the future.Therefore the investigation of 2018 flood disaster at the Baige landslide is of a great significance to provide a classic case for flood assessment and early warning for the future disaster.The detailed survey revealed that the outstanding inundations induced bank collapse disasters upstream the Baige landslide dams,and the field investigations and hydrological simulation suggested that the downstream of the Baige landslide were seriously flooded due to the two periods of the outburst floods.On these bases,the early warning process of potential outburst floods at the Baige landslide was advised,which contains four stages:Outburst Flood Simulating Stage,Outburst Flood Forecasting Stage,Emergency Plan and Emergency Evacuation Stage.The study offers a conceptual model for the mitigation of landslides and flood disasters in the high-relief mountain-ous region in Tibet.
基金supported by the National Natural Science Foundation of China (U2240221)the Sichuan Youth Science and Technology Innovation Research Team Project (2020JDTD0006)。
文摘Rainwater runoff that does not infiltrate the soil during heavy rainfall may increase slope instability. The effect of runoff is usually neglected in conventional rainfall-induced slope failure analysis to simplify the model. To analyze the effect of runoff on slope stability, this study simultaneously simulated the effects of surface runoff and rainfall infiltration on bank slopes in the Three Gorges Reservoir Area. A shallow slope failure method that can be used to analyze runoff was proposed based on the modified Green-Ampt model, the simplified Saint-Venant model, and the infinite slope model. In this model, the modified Green–Ampt model was used to estimate the rainfall infiltration capacity and the wetting front depth. The eight-flow(D8) method and the simplified Saint-Venant model were selected to estimate the distribution of runoff. By considering the wetting front depth as the slip surface depth, the factor of safety of the slope could be determined using the infinite slope stability model. A comparison of the different models reveals that runoff can escalate the instability of certain slopes, causing stable slopes to become unstable. Comparison of the unstable areas obtained from the simulation with the actual landslide sites shows that the model proposed in this study can successfully predict landslides at these sites. The slope instability assessment model proposed in this study offers an alternative approach for estimating high-risk areas in large mountainous regions.
基金financially supported by the Key Laboratory of Estuarine&Coastal Engineering,Ministry of Transport Open Research Program (Grant No.KLECE202001)CRSRI Open Research Program (Grant No.CKWV20221007/KY)+4 种基金the National Natural Science Foundation of China (Grant No.51979172)Jiangsu Provincial Water Conservancy Technology Project (Grant Nos.2020002,2021025,and 2021029)Fundamental Research Funds for Central Public Welfare Research Institutes (Y223002)Innovation Team Project of Estuarine and Coastal Protection and Management (Grant No.Y220013)the Major Scientific Projects of the Ministry of Water Resources (Grant No.SKS-2022087)。
文摘In recent years,regional floods and typhoons have occurred in the Yangtze Estuary.Changing dynamic conditions and dramatic reduction of sediment discharge in the basin are affecting the dynamic equilibrium pattern of the Yangtze Estuary.Based on the field measurement data and theoretical derivation,this paper analyzed the changing process of runoff-sediment discharge into the sea after the operation of the Three Gorges Project(TGP),and the tidal dynamics and sediment variation characteristics of the Yangtze Estuary.The erosion of South Branch mainly occurs in the channel below-10 m contour,and the riverbed volume below contours 0 m and-10 m has a good correlation with the sediment discharge of Datong Station in the previous year.On this basis,the ratio of the horizontal distance from the starting point to the section centroid below the average water level(B_c)and the water depth at the section centroid(H_c)was proposed to describe the change of the section shape.The relationships between the water-diverting ratio,the sediment-diverting ratio and the water-diverting angle,the conditions of runoff and sediment discharge from the upper reach and the characteristics of the riverway section were established,and the theoretical calculation equations of the water-diverting ratio,the sediment-diverting ratio and the diverting angle of each bifurcation were also established.
基金supported by the National Natural Science Foundation of China (51639007)the Youth Science and Technology Fund of Sichuan Province (2016JQ0011)the Science and Technology Fund of Chengdu Water Authority (14H1055).
文摘Flexible net barriers are a new type of effective mitigation measure against debris flows in valleys and can affect the kinematic energy and mass of debris flows. Here, ten flume tests were performed to study the dynamic behaviours of debris flows with differences in volumes, concentrations(solid volume fraction), and travel distances after interception by a uniform flexible net barrier. A high-speed camera was used to monitor the whole test process, and their dynamic behaviours were recorded. A preliminary computational framework on energy conversion is proposed according to the deposition mechanisms and outflow of debris flow under the effects of the flexible net barrier. The experimental results show that the dynamic interaction process between a debris flow and the flexible net barrier can be divided into two stages:(a) the two-phase impact of the leading edge of the debris flow with the net and(b) collision and friction between the body of the debris flow and intercepted debris material. The approach velocity of a debris flow decreases sharply(a maximum of 63%) after the interception by the net barrier, and the mass ratio of the debris material being intercepted and the kinetic energy ratio of the debris material being absorbed by the net barrier are close due to the limited interception efficiency of the flexible net barrier, which is believed to be related to the flexibility. The energy ratio of outflow is relative small despite the large permeability of the flexible net barrier.
基金supported by the National Natural Science Foundations of China(grant numbers U22A20601 and 52209142)the Opening fund of State Key Laboratory of Geohazard Prevention and Geoenvironment Protection(Chengdu University of Technology)(grant number SKLGP2022K018)+1 种基金the Science&Technology Department of Sichuan Province(grant number 2023NSFSC0284)the Science and Technology Major Project of Tibetan Autonomous Region of China(grant number XZ202201ZD0003G)。
文摘Accurate dynamic modeling of landslides could help understand the movement mechanisms and guide disaster mitigation and prevention.Discontinuous deformation analysis(DDA)is an effective approach for investigating landslides.However,DDA fails to accurately capture the degradation in shear strength of rock joints commonly observed in high-speed landslides.In this study,DDA is modified by incorporating simplified joint shear strength degradation.Based on the modified DDA,the kinematics of the Baige landslide that occurred along the Jinsha River in China on 10 October 2018 are reproduced.The violent starting velocity of the landslide is considered explicitly.Three cases with different violent starting velocities are investigated to show their effect on the landslide movement process.Subsequently,the landslide movement process and the final accumulation characteristics are analyzed from multiple perspectives.The results show that the violent starting velocity affects the landslide motion characteristics,which is found to be about 4 m/s in the Baige landslide.The movement process of the Baige landslide involves four stages:initiation,high-speed sliding,impact-climbing,low-speed motion and accumulation.The accumulation states of sliding masses in different zones are different,which essentially corresponds to reality.The research results suggest that the modified DDA is applicable to similar high-level rock landslides.
基金study was funded by the National Natural Science Foundation of China(grant number:U20A2080,31622015)Sichuan University(Fundamental Research Funds for the Central Universities,SCU2021D006,SCU2020D003).
文摘Elevation plays a crucial factor in the distribution of plants,as environmental conditions become increasingly harsh at higher elevations.Previous studies have mainly focused on the effects of large-scale elevational gradients on plants,with little attention on the impact of smaller-scale gradients.In this study we used 14 microsatellite loci to survey the genetic structure of 332 Juniperus squamata plants along elevation gradient from two sites in the Hengduan Mountains.We found that the genetic structure(single,clonal,mosaic)of J.squamata shrubs is affected by differences in elevational gradients of only 150 m.Shrubs in the mid-elevation plots rarely have a clonal or mosaic structure compared to shrubs in lower-or higher-elevation plots.Human activity can significantly affect genetic structure,as well as reproductive strategy and genetic diversity.Sub-populations at mid-elevations had the highest yield of seed cones,lower levels of asexual reproduction and higher levels of genetic diversity.This may be due to the trade-off between elevational stress and anthropogenic disturbance at mid-elevation since there is greater elevational stress at higher-elevations and greater intensity of anthropogenic disturbance at lower-elevations.Our findings provide new insights into the finer scale genetic structure of alpine shrubs,which may improve the conservation and management of shrublands,a major vegetation type on the Hengduan Mountains and the Qinghai-Tibet Plateau.
基金The authors are grateful for the financial support from the National Natural Science Foundation of China(Grant Nos.52225904 and 52039007)the Natural Science Foundation of Sichuan Province(Grant No.2023NSFSC0377)supported by the New Cornerstone Science Foundation through the XPLORER PRIZE.
文摘Exploring dynamic mechanical responses and failure behaviors of hot dry rock(HDR)is significant for geothermal exploitation and stability assessment.In this study,via the split Hopkinson pressure bar(SHPB)system,a series of dynamic compression tests were conducted on granite treated by cyclic thermal shocks at different temperatures.We analyzed the effects of cyclic thermal shock on the thermal-related physical and dynamic mechanical behaviors of granite.Specifically,the P-wave velocity,dynamic strength,and elastic modulus of the tested granite decrease with increasing temperature and cycle number,while porosity and peak strain increase.The degradation law of dynamic mechanical properties could be described by a cubic polynomial.Cyclic thermal shock promotes shear cracks propagation,causing dynamic failure mode of granite to transition from splitting to tensile-shear composite failure,accompanied by surface spalling and debris splashing.Moreover,the thermal shock damage evolution and coupled failure mechanism of tested granite are discussed.The evolution of thermal shock damage with thermal shock cycle numbers shows an obvious S-shaped surface,featured by an exponential correlation with dynamic mechanical parameters.In addition,with increasing thermal shock temperature and cycles,granite mineral species barely change,but the length and width of thermal cracks increase significantly.The non-uniform expansion of minerals,thermal shock-induced cracking,and water-rock interaction are primary factors for deteriorating dynamic mechanical properties of granite under cyclic thermal shock.
基金supported by National Natural Science Foundation of Joint Fund for Changjiang River Water Science Research(U2340201)National Natural Science Foundation of China(52239006)Natural Science Foundation of Sichuan Province(2024NSFSC0005).
文摘Rainstorm-induced flood hazards in mountainous areas often result in complex cascading effects by interacting with environmental and human systems.However,traditional studies typically categorize them simply as clearwater floods or debris floods/flows,overlooking their evolutionary characteristics and compound impacts.This study presents a novel classification-based approach to investigate the formation and destructive mechanisms of a catastrophic composite disaster of flash flood and debris flow in the Dayao Gully(DYG)catchment in Hanyuan County,Sichuan Province,China.The event resulted in 14 fatalities,25 missing persons,and extensive infrastructure damage.Through comprehensive field investigations and multi-method analysis,three distinct disaster zones were identified with different magnitudes and impacts:(1)a clearwater flood disaster region with minimal geomorphological changes under a 5-year return period rainfall;(2)a debris flood disaster region triggered by a 30-year return period rainfall,leading to intense sediment transport with a total deposit volume of 52,511 m^(3);and(3)a sediment-induced flood disaster region characterized by significant riverbed aggradation and infrastructure destruction due to sediment-induced blockage effects.The results reveal that the cascading characteristics of this composite disaster were primarily driven by intense rainfall,enhanced sediment transport motivated by supracritical shear stress,and interactions with human infrastructure(e.g.,bridges and buildings).This classification-based approach provides a quantitative assessment of spatial characteristics of cascading flood disasters,offering new insights into their evolutionary characteristics and highlighting the necessity for targeted disaster mitigation strategies in sedimentprone mountainous regions.
基金fund support was received from Sichuan Philosophy and Social Science Foundation Program[Grant No.SCJJ24ND066].
文摘New energy vehicles are distinguished by their environmentally friendly characteristics;however,their sales remain low compared with those of fossil fuel vehicles.This study identifies the key factors influencing consumer purchases of new energy vehicles with the aim of increasing sales and promoting the development of the new energy vehicle industry.Machine learning(ML)techniques were employed to analyze more than 26000 consumer reviews of new energy vehicles and identify the factors influencing their purchasing decisions.Subsequently,a hybrid simulation model was constructed using the complex adaptive system framework.The model combines the strengths of ML,multi-agent modeling,and system dynamics modeling,thereby enhancing its capacity to identify key factors.The model comprises two categories of manufacturers:producers of new energy vehicles and producers of fossil fuel vehicles.Dynamic simulations were conducted using the AnyLogic simulation platform.The findings indicated a negative correlation between consumer income and demand for new energy vehicles.Conversely,expansions in the interior space of new energy vehicles and favorable consumer perceptions of their environmental benefits have contributed to increased demand for these vehicles.Therefore,rather than exclusively focusing on price advantages,it would be more beneficial to prioritize expanding new energy vehicles’interior space and disseminating information about their environmental benefits to consumers.It seems reasonable to posit that these strategies would increase consumer willingness to purchase new energy vehicles in the long term.
基金support of the National Natural Science Foundation of China(U42107189,20A20111).
文摘Landslide dam failures can cause significant damage to both society and ecosystems.Predicting the failure of these dams in advance enables early preventive measures,thereby minimizing potential harm.This paper aims to propose a fast and accurate model for predicting the longevity of landslide dams while also addressing the issue of missing data.Given the wide variation in the survival times of landslide dams—from mere minutes to several thousand years—predicting their longevity presents a considerable challenge.The study develops predictive models by considering key factors such as dam geometry,hydrodynamic conditions,materials,and triggering parameters.A dataset of 1045 landslide dam cases is analyzed,categorizing their longevity into three distinct groups:C1(<1 month),C2(1 month to 1 year),and C3(>1 year).Multiple imputation and knearest neighbor algorithms are used to handle missing data on geometric size,hydrodynamic conditions,materials,and triggers.Based on the imputed data,two predictive models are developed:a classification model for dam longevity categories and a regression model for precise longevity predictions.The classification model achieves an accuracy of 88.38%while the regression model outperforms existing models with an R^(2) value of 0.966.Two real-life landslide dam cases are used to validate the models,which show correct classification and small prediction errors.The longevity of landslide dams is jointly influenced by factors such as geometric size,hydrodynamic conditions,materials,and triggering events.Among these,geometric size has the greatest impact,followed by hydrodynamic conditions,materials,and triggers,as confirmed by variable importance in the model development.
基金Projects(U23A2060,42177143)supported by the National Natural Science Foundation of China。
文摘To elucidate the influence of confining pressure on microcrack evolution and macroscopic failure mechanisms in granite,a multi-perspective approach was adopted.This approach combined triaxial compression tests,acoustic emission(AE)monitoring,and PFC simulations.The results show that:1)Confining pressure exhibits a pronounced linear correlation with both yield strength and compressive strength.The enhancement of confining pressure significantly improves the deformability of granite and promotes a progressive shift in failure mechanism from brittle rupture to ductile deformation;2)Increasing confining pressure elevates the stress threshold for microcrack initiation and suppresses crack propagation.As a result,the proportion of shear cracks increases(based on AE analysis)from 18.71%to 61.2%,marking a transition in the dominant failure mode from tensile to shear;3)Confining pressure facilitates the development of grain boundary shear cracks(GBSCs),establishing the primary damage pathways.In addition,local stress concentrations under high confinement conditions trigger intragranular cracking.This highlights the regulatory effect of confining pressure on microcrack evolution.
