Extensive identification of landslide boundaries using remote sensing images and deep learning method

The frequent occurrence of extreme weather events has rendered numerous landslides to a global natural disaster issue.It is crucial to rapidly and accurately determine the boundaries of landslides for geohazards evaluation and emergency response.Therefore,the Skip Connection DeepLab neural network(SCDnn),a deep learning model based on 770 optical remote sensing images of landslide,is proposed to improve the accuracy of landslide boundary detection.The SCDnn model is optimized for the over-segmentation issue which occurs in conventional deep learning models when there is a significant degree of similarity between topographical geomorphic features.SCDnn exhibits notable improvements in landslide feature extraction and semantic segmentation by combining an enhanced Atrous Spatial Pyramid Convolutional Block(ASPC)with a coding structure that reduces model complexity.The experimental results demonstrate that SCDnn can identify landslide boundaries in 119 images with MIoU values between 0.8and 0.9;while 52 images with MIoU values exceeding 0.9,which exceeds the identification accuracy of existing techniques.This work can offer a novel technique for the automatic extensive identification of landslide boundaries in remote sensing images in addition to establishing the groundwork for future inve stigations and applications in related domains.

Modelling of debris-flow susceptibility and propagation: a case study from Northwest Himalaya

The geological and geographical position of the Northwest Himalayas makes it a vulnerable area for mass movements particularly landslides and debris flows. Mass movements have had a substantial impact on the study area which is extending along Karakorum Highway(KKH) from Besham to Chilas. Intense seismicity, deep gorges, steep terrain and extreme climatic events trigger multiple mountain hazards along the KKH, among which debris flow is recognized as the most destructive geohazard. This study aims to prepare a field-based debris flow inventory map at a regional scale along a 200 km stretch from Besham to Chilas. A total of 117 debris flows were identified in the field, and subsequently, a point-based debris-flow inventory and catchment delineation were performed through Arc GIS analysis. Regional scale debris flow susceptibility and propagation maps were prepared using Weighted Overlay Method(WOM) and Flow-R technique sequentially. Predisposing factors include slope, slope aspect, elevation, Topographic Roughness Index(TRI), Topographic Wetness Index(TWI), stream buffer, distance to faults, lithology rainfall, curvature, and collapsed material layer. The dataset was randomly divided into training data(75%) and validation data(25%). Results were validated through the Receiver Operator Characteristics(ROC) curve. Results show that Area Under the Curve(AUC) using WOM model is 79.2%. Flow-R propagation of debris flow shows that the 13.15%, 22.94%, and 63.91% areas are very high, high, and low susceptible to debris flow respectively. The propagation predicated by Flow-R validates the naturally occurring debris flow propagation as observed in the field surveys. The output of this research will provide valuable input to the decision makers for the site selection, designing of the prevention system, and for the protection of current infrastructure.

Multiscale evolution mechanism of sandstone under wet-dry cycles of deionized water:From molecular scale to macroscopic scale

Water is the most abundant molecule found on the earth’s surface and is a key factor in multiscale rock destruction.However,given the fine-grained nature of rock and the complexity of its internal structure,the microstructural evolution of rock under the action of water has not yet been elucidated in detail,and little is understood about the relationship between the rock structure and solideliquid unit.A variety of techniques were used in this study to track the mechanical properties,pore and crack characteristics,and mineral structure degradation characteristics of sandstone at different stages under the action of deionized water,and the evolution mechanisms of the microstructure were analyzed at the molecular scale.The results showed that during the watererock interaction process,water was adsorbed onto the surface of dolomite minerals and the hydrophilic surface of clay minerals,forming a high-density hydrogen bond network.However,different mineral surface structures had different water adsorption structures,resulting in the strain of the dense clay mineral aggregates under expansion action.Stress concentrated at crack tips under the capillary force of dolomite minerals(very weak dolomite dissolution).These effects resulted in a substantial increase in the number of small pores and enhancements in poreecrack connectivity,and the rock strength exhibited varying degrees of decline at different stages of wet-dry cycles.In general,the results of this paper will help to further elucidate the internal connections between molecular-scale and macroscale processes in rock science.

Numerical manifold method for thermo-mechanical coupling simulation of fractured rock mass

As a calculation method based on the Galerkin variation,the numerical manifold method(NMM)adopts a double covering system,which can easily deal with discontinuous deformation problems and has a high calculation accuracy.Aiming at the thermo-mechanical(TM)coupling problem of fractured rock masses,this study uses the NMM to simulate the processes of crack initiation and propagation in a rock mass under the influence of temperature field,deduces related system equations,and proposes a penalty function method to deal with boundary conditions.Numerical examples are employed to confirm the effectiveness and high accuracy of this method.By the thermal stress analysis of a thick-walled cylinder(TWC),the simulation of cracking in the TWC under heating and cooling conditions,and the simulation of thermal cracking of the SwedishÄspöPillar Stability Experiment(APSE)rock column,the thermal stress,and TM coupling are obtained.The numerical simulation results are in good agreement with the test data and other numerical results,thus verifying the effectiveness of the NMM in dealing with thermal stress and crack propagation problems of fractured rock masses.

Evaluation of the treatment effect of rear slope cutting on hydrodynamic pressure landslides:A case study

After the impoundment of the Three Gorges Reservoir,some huge ancient landslides were reactivated and deformed,showing typical hydrodynamic pressure landslide characteristics.The Baishuihe landslide was a typical hydrodynamic pressure landslide.The management department conducted slope cutting treatments from 2018 to 2019.To evaluate the treatment effect of rear slope cutting,this study analyzed the data of the surface deformation survey and field monitoring over the past 20 years and the characteristics of the reservoir water-triggered Baishuihe landslide deformation,and calculated the seepage field,displacement field,and stability coefficient before and after landslide treatment.The results showed that the deformation of the Baishuihe landslide was primarily related to a decrease in the reservoir water level.Owing to the poor permeability of the landslide soil,the decrease in the reservoir water level produced a seepage force pointing to the outside of the landslide body,leading to the step deformation of the landslide displacement.The landslide was treated by rear slope cutting,and the“step”deformation of the landslide disappeared after treatment.The hydrodynamic pressure caused by the change in reservoir water after cutting the slope did not disappear.However,as the slope cutting greatly reduced the overall sliding force of the landslide,its stability was greatly improved.Notably,high stability can still be ensured under extreme rainfall after treatment.Slope cutting is effective for treating hydrodynamic pressure landslides.This study can provide effective technical support for the treatment of reservoir landslides.

Rheological mechanical properties and its constitutive relation of soft rock considering influence of clay mineral composition and content

Rheological mechanical properties of the soft rock are afected signifcantly by its main physical characteristics-clay mineral.In this study,taking the mudstone on the roof and foor in four typical mining regions as the research object,frstly,the clay mineral characteristic was analyzed by the X-ray difraction test.Subsequently,rheological mechanical properties of mudstone samples under diferent confning pressures are studied through triaxial compression and creep tests.The results show that the clay mineral content of mudstone in diferent regions is diferent,which leads to signifcant diferences in its rheological properties,and these diferences have a good correlation with the content of montmorillonite and illite-montmorillonite mixed layer.Taking the montmorillonite content as an example,compared with the sample with 3.56%under the lower stress level,the initial creep deformation of the sample with 11.19%increased by 3.25 times,the viscosity coefcient and longterm strength decreased by 80.59%and 53.94%,respectively.Furthermore,based on the test results,the damage variation is constructed considering the montmorillonite content and stress level,and the M–S creep damage constitutive model of soft rock is established.Finally,the test results can be ftted with determination coefcients ranging from 0.9020 to 0.9741,which proves that the constitutive relation can refect the infuence of the clay mineral content in the samples preferably.This study has an important reference for revealing the long-term stability control mechanism of soft rock roadway rich in clay minerals.

Algorithmic approach to discrete fracture network flow modeling in consideration of realistic connections in large-scale fracture networks

Analyzing rock mass seepage using the discrete fracture network(DFN)flow model poses challenges when dealing with complex fracture networks.This paper presents a novel DFN flow model that incorporates the actual connections of large-scale fractures.Notably,this model efficiently manages over 20,000 fractures without necessitating adjustments to the DFN geometry.All geometric analyses,such as identifying connected fractures,dividing the two-dimensional domain into closed loops,triangulating arbitrary loops,and refining triangular elements,are fully automated.The analysis processes are comprehensively introduced,and core algorithms,along with their pseudo-codes,are outlined and explained to assist readers in their programming endeavors.The accuracy of geometric analyses is validated through topological graphs representing the connection relationships between fractures.In practical application,the proposed model is employed to assess the water-sealing effectiveness of an underground storage cavern project.The analysis results indicate that the existing design scheme can effectively prevent the stored oil from leaking in the presence of both dense and sparse fractures.Furthermore,following extensive modification and optimization,the scale and precision of model computation suggest that the proposed model and developed codes can meet the requirements of engineering applications.

The Practical Path of Labor Curriculum in Compulsory Education in China from the Perspective of Overlapping Influence Domain Theory

Since the new curriculum reform,labor education has gradually shed its marginalized position in the“five educations,”and the labor curriculum has become an independent course officially separated from comprehensive practical activity courses.Exploring the practical path of labor curriculum in compulsory education in China has become the primary task of labor education in China.Based on the practical situation of labor curriculum in compulsory education in China,drawing on the theory of overlapping influence domains,and from the perspective of collaborative education among family,school,and community,this paper proposes a curriculum practical path of“school-led”family-school-community collaboration and a curriculum practical path guided by“student-centered”sentiment,in order to provide references for the practice of labor curriculum in compulsory education in China.

Preliminary report of the September 5,2022 M_(S) 6.8 Luding earthquake,Sichuan,China

The 2022 M_(S)6.8 Luding earthquake is the strongest earthquake in Sichuan Province, Western China, since the 2017 M_(S)7.0 Jiuzhaigou earthquake. It occurred on the Moxi fault in the southeastern segment of the Xianshuihe fault, a tectonically active and mountainous region with severe secondary earthquake disasters. To better understand the seismogenic mechanism and provide scientific support for future hazard mitigation, we summarize the preliminary results of the Luding earthquake, including seismotectonic background, seismicity and mainshock source characteristics and aftershock properties, and direct and secondary damage associated with the mainshock.The peak ground displacements in the NS and EW directions observed by the nearest GNSS station SCCM are ~35 mm and ~55 mm, respectively, resulting in the maximum coseismic dislocation of 20 mm along the NWW direction, which is consistent with the sinistral slip on the Xianshuihe fault. Back-projection of teleseismic P waves suggest that the mainshock rupture propagated toward south-southeast. The seismic intensity of the mainshock estimated from the back-projection results indicates a Mercalli scale of Ⅷ or above near the ruptured area,consistent with the results from instrumental measurements and field surveys. Numerous aftershocks were reported, with the largest being M_(S)4.5. Aftershock locations(up to September 18, 2022) exhibit 3 clusters spanning an area of 100 km long and 30 km wide. The magnitude and rate of aftershocks decreased as expected, and the depths became shallower with time. The mainshock and two aftershocks show left-lateral strike-slip focal mechanisms. For the aftershock sequence, the b-value from the Gutenberg-Richter frequency-magnitude relationship, h-value, and p-value for Omori’s law for aftershock decay are 0.81, 1.4, and 1.21, respectively, indicating that this is a typical mainshock-aftershock sequence. The low b-value implies high background stress in the hypocenter region. Analysis from remote sensing satellite images and UAV data shows that the distribution of earthquake-triggered landslides was consistent with the aftershock area. Numerous small-size landslides with limited volumes were revealed, which damaged or buried the roads and severely hindered the rescue process.

Upper-Bound Limit Analysis of the Multi-Layer Slope Stability and Failure Mode Based on Generalized Horizontal Slice Method

Multi-layer slopes are widely found in clay residue receiving fields.A generalized horizontal slice method(GHSM)for assessing the stability of multi-layer slopes that considers the energy dissipation between adjacent horizontal slices is presented.In view of the upper-bound limit analysis theory,the energy equation is derived and the ultimate failure mode is generated by comparing the sliding surface passing through the slope toe(mode A)with that below(mode B).In addition,the influence of the number of slices on the stability coefficients in the GHSM is studied and the stable value is obtained.Compared to the original method(Chen’s method),the GHSM can acquire more precise results,which takes into account the energy dissipation in the inner sliding soil mass.Moreover,the GHSM,limit equilibrium method(LEM)and numerical simulation method(NSM)are applied to analyze the stability of a multi-layer slope with different slope angles and the results of the safety factor and failure mode are very close in each case.The ultimate failure modes are shown to be mode B when the slope angle is not more than 28°.It illustrates that the determination of the ultimate sliding surface requires comparison of multiple failure modes,not only mode A.

Insight into the Permeability and Microstructure Evolution Mechanism of the Sliding Zone Soil: A Case Study from the Huangtupo Landslide, Three Gorges Reservoir, China

A large number of laboratory investigations related to the permeability have been conducted on the sliding zones.Yet little attention has been paid to the particular sliding zones of the slideprone Badong Formation.Here,we experimentally investigate the permeability nature and the mechanism of seepage in the viscous sliding zone of the Huangtupo Landslide.Saturated seepage tests have been performed first with consideration of six dry densities and thirteen hydraulic gradients,in conjunction with the mercury intrusion porosimetry test and scanning electron microscopy test for the microstructure analysis after seepage.The results show that seepage in the sliding zone soil does not follow Darcy’s Law,since there is a threshold hydraulic gradient(i0)below which no flow is observed and a critical hydraulic gradient(icr)over which the hydraulic conductivity(K)tends to be stable.The percentage of bound water could be responsible for the occurrence of i0 and icr.Furthermore,pore size distributions(PSD)less than 0.6µm and between 10 and 90µm exhibit positive and negative correlations with the i0,respectively,indicating that the i0 is related to the PSD.The mechanism accounting for this result is that pore water pressure forces fine clay particles into the surrounding large pores and converts arranged particles to discretely distributed ones,thereby weakening the connectivity of pores.The seepages in the sliding zones behave differently from that in the sliding mass and sliding bed in response to the permeability.

A stability evaluation method for deep-seated toppling in the upper Lancang river,Southwestern China

Deep-seated toppling in the upper reaches of the Lancang River,southwest China involves deformations exceeding 100 m in depth.The slope deformation is initiated by river downcutting and evolves distinctive characteristics with a depth of river incision.In this study,we propose a system for evaluating the stability of deep-seated toppled slopes in different evolutionary stages.This system contains identification criteria for each evolutionary stage and provides the corresponding stability evaluation methods.Based on the mechanical and kinematic analysis of slope blocks,the specific stage of slope movement can be identified in the field through outcrop mapping,in situ tests,surface displacement monitoring,and adit and borehole explorations.The stability evaluation methods are established based on the limiting equilibrium theory and the strain compatibility between the undisturbed zone and the toppled zone.Finally,several sample slopes in different evolution stages have been investigated to verify the applicability and accuracy of the proposed stability evaluation system.The results indicate that intense tectonic activity and rapid river incision lead to a maximum principal stress ratio exceeding 10 near the slope surface,thus triggering widespread toppling deformations along the river valley.When considering the losses of joint cohesion during the further rotation process,the safety factor of the slope drops by 7%e28%.The self-stabilization of toppling deformation can be recognized by the layer symmetry configuration after the free rotation of the deflected layers.Intensely toppled rock blocks mainly suffer sliding failures beyond the layer symmetry condition.The factor of safety of the K73 rockslide decreased from 1.17 to 0.87 by considering the development of the potential sliding surface and the toesaturated zone.

A Three-Dimensional DEM Method for Trajectory Simulations of Rockfall under Irregular-Shaped Slope Surface and Rock Blocks

0 INTRODUCTION.Rockfall is a common geological hazard that poses a serious threat to residents and infrastructures(Gao et al.,2022;Ye et al.,2022).The precise prediction of rockfall trajectories is essential to the design of protection engineering structures of rockfall(Ma et al.,2021).The discrete element modelling(DEM)is increasingly used to analyse rockfall movement paths.Ma et al.(2022)used Rockyfor3D software to obtain the possible trajectory of falling rock blocks.

Application of artificial intelligence in three aspects of landslide risk assessment: A comprehensive review

Landslides are one of the geological disasters with wide distribution,high impact and serious damage around the world.Landslide risk assessment can help us know the risk of landslides occurring,which is an effective way to prevent landslide disasters in advance.In recent decades,artificial intelligence(AI)has developed rapidly and has been used in a wide range of applications,especially for natural hazards.Based on the published literatures,this paper presents a detailed review of AI applications in landslide risk assessment.Three key areas where the application of AI is prominent are identified,including landslide detection,landslide susceptibility assessment,and prediction of landslide displacement.Machine learning(ML)containing deep learning(DL)has emerged as the primary technology which has been considered successfully due to its ability to quantify complex nonlinear relationships of soil structures and landslide predisposing factors.Among the algorithms,convolutional neural networks(CNNs)and recurrent neural networks(RNNs)are two models that are most widely used with satisfactory results in landslide risk assessment.The generalization ability,sampling training strategies,and hyperparameters optimization of these models are crucial and should be carefully considered.The challenges and opportunities of AI applications are also fully discussed to provide suggestions for future research in landslide risk assessment.

Centrifuge modelling of landslides and landslide hazard mitigation:A review

Landslides are serious geohazards that occur under a variety of climatic conditions and can cause many casualties and significant economic losses.Centrifuge modelling,as a representative type of physical modelling,provides a realistic simulation of the stress level in a small-scale model and has been applied over the last 50 years to develop a better understanding of landslides.With recent developments in this technology,the application of centrifuge modelling in landslide science has significantly increased.Here,we present an overview of physical models that can capture landslide processes during centrifuge modelling.This review focuses on(i)the experimental principles and considerations,(ii)landslide models subjected to various triggering factors,including centrifugal acceleration,rainfall,earthquakes,water level changes,thawing permafrost,excavation,external loading and miscellaneous conditions,and(iii)different methods for mitigating landslides modelled in centrifuge,such as the application of nails,piles,geotextiles,vegetation,etc.The behaviors of all the centrifuge models are discussed,with emphasis on the deformation and failure mechanisms and experimental techniques.Based on this review,we provide a best-practice methodology for preparing a centrifuge landslide test and propose further efforts in terms of the seven aspects of model materials,testing design and equipment,measurement methods,scaling laws,full-scale test applications,landslide early warning,and 3D modelling to better understand the complex behaviour of landslides.

Genetic Mechanism of Water-Rich Landslide Considering Antecedent Rainfalls:A Case Study of Pingyikou Landslide in Three Gorges Reservoir Area

Water-rich slope,which could easily fail after prolonged or heavy rain,is very sensitive to rainfall.Pingyikou Landslide is a typical water-rich slope located in the Three Gorges Reservoir area of China.It was unstable because of the continuous rainfall that occurred from September to October 2017.To understand the deformation process and genetic mechanism of the landslide,the geomorphological features,geological characteristics,hydrological conditions,and rainfall characteristics were systematically studied by a detailed field investigation of the slope and monitoring of rainfall,water level,and displacement.In addition,the influence of different initial conditions on the stability of the slope was also studied through numerical simulation using measured rainfall data on the basis of which,the effect of antecedent rainfall on slope stability was studied by unsaturated seepage analysis method.The results show that the deformation of slope is strongly correlated with the rainfall and groundwater level,and this landslide is a typical rainfall-induced landslide.In the analysis of genetic mechanism of the same type of landslide,a maximum initial pore water pressure of -25 kPa as the initial condition is reasonable.And the antecedent rainfall has a greater effect on the stability of the slope,more than 10 days of antecedent rainfall should be considered when designing and controling the slope.

Characterization of Macro-and Meso-Scale Shear Behavior of Soil-Brick Mixtures with Different Contents and Shapes of Brick by Discrete Element Method

Due to urban construction and renovation projects,a large amount of construction and demolition waste(CDW)is increasing year by year in China.Among them,soil-brick mixture(SBM)is most widely landfilled because many older brick buildings were constructed in the last century(Zhang et al.,2022;Xu et al.,2021).Since the SBM is composed of two kinds of geotechnical materials,its mechanical properties are more complex than those of the single material.They depend not only on the mechanical properties of the individual components such as soil and brick,but also on the relative content of these components and the shape of the coarse particles(Zhu et al.,2021).The shear properties of SBM directly affect the stability of slope and paving engineering;therefore,it is significant to study the mechanical properties of SBM.

Integrating Shipborne Images with Multichannel Deep Learning for Landslide Detection

0 INTRODUCTION.Landslide disasters in recession zones along riverbanks impose significant global social,economic,and ecological damage.These areas are particularly susceptible to landslides.They inflict significant harm due to fluctuating water levels(Meng et al.,2023;Dai et al.,2021;Li et al.,2021).This,in turn,endangers the safety and accessibility of roads and waterways adjacent to rivers,and hydropower station and reservoir security(Yan et al.,2022;Guo et al.,2020;Tang et al.,2017).

Compression Characteristic and Creep Behavior of Moraine Soil at Xingkang Bridge,West Sichuan,China

The compression and creep characteristics of moraine soil are important mechanical properties of geomaterials to be analyzed during the construction process of engineering projects.However,related references about these characteristics through large-size in-situ tests have rarely been reported.In this study,in-situ tests of particle size distribution,compression deformation,and compression creep were conducted at the Xingkang Bridge,West Sichuan,China.The results show that the uniformity coefficient of moraine soil ranges from 12.1 to 183.3,and gradation coefficient ranges from 0.4 to 2.8.The total compression deformations of moraine samples during the conventional compression deformation test are 4.70,4.07,and 0.47 mm,and their residual deformations are 2.81,2.45,and 0.22 mm,respectively.The deformation modulus ranges from 127.3 to 676.4 MPa,and elastic modulus ranges from 316.3 to 765.7 MPa.During compression creep tests,moraine soil enters the steady creep stage after 3.8 h of loading pressure at 445 k Pa,and it keeps steady after 14 h of loading pressure at 900 k Pa.The Burgers model and generalized Kelvin model predict the deformation well in transient,deceleration and steady creep stages.Results provide a valuable reference for the analysis of the compression deformation and creep behavior of moraine soil during engineering construction and management.

30 Years of Climate Change before and after the Impoundment of the Three Gorges Reservoir

The Three Gorges Project, also known as the Yangtze River Three Gorges Water Control Project, is located in Yichang, Hubei Province, China. The dam is one of the largest hydropower stations in the world, with an elevation of 185 meters and a water storage elevation of 175 meters.