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Stability analysis of complex terrain slope based on multi-source point cloud fusion

Journal of Mountain Science 2022年第9期19卷 2703-2714页

作者： ZAN Wen-bo ZHANG Wen-jie WANG Ning ZHAO Chun-chen YANG Qian LI Hao School of Highway Chang’an UniversityXi’an 710064China Research and Development Center for Loess Mechanics and Engineering Test Technology Shaanxi Polytechnic InstituteXianyang 712000China School of Automobile Chang’an UniversityXi’an 710064China

Numerical modelling is a common routine for slope stability analysis in the complex terrain,and the accuracy of topographic survey has a great impact on the results.In this study,a combination of unmanned aerial vehicle(UAV)photogrammetry and 3D laser scanning technique was first proposed to establish a high-precision digital elevation model(DEM),which could be accurate to 0.2 m,fulfilling the engineering requirements.Then,a series of 3D/2D finite element models(FEM)were constituted on the basis of DEM to investigate the slope stability in the complex terrain.The results indicate that the deformation of complex terrain slope is chiefly triggered by compression-shear failure and the failure zones are mostly distributed on the middle-upper part and the scarp.Furthermore,the complex terrain slope is divided into concave,convex,concave-convex and convex-concave slope according to the topographical curvature,and the factor of safety(FOS)is as follows:the maximum value 1.8504 for the concave-convex slope,the minimum value 1.1129 for the convexconcave slope,and the median for either concave or convex slope.The inflection points and curvature of the slope jointly determine the shape of nonlinear slope,dominating the morphological effect on the slope stability,so the rational use of section morphological effect will be conducive to the overall stability of the slope.For four representative slopes,the plastic deformation first emerges into the middle,then progressively develops to the upper,and finally forms the connected failure zones.

关键词： Slope stability complex terrain DEM Numerical simulation Plastic zone Factor of Safety

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Correction of CMPAS Precipitation Products over complex terrain Areas with Machine Learning Models

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Journal of Tropical Meteorology 2023年第2期29卷 264-276页

作者：李施颖黄晓龙吴薇杜冰蒋雨荷 Sichuan Meteorological Observation and Data Center Chengdu 610072 China Heavy Rain and Drought-flood Disasters in Plateau and Basin Key Laboratory of Sichuan Province Chengdu 610072 China

Machine learning models were used to improve the accuracy of China Meteorological Administration Multisource Precipitation Analysis System(CMPAS)in complex terrain areas by combining rain gauge precipitation with topographic factors like altitude,slope,slope direction,slope variability,surface roughness,and meteorological factors like temperature and wind speed.The results of the correction demonstrated that the ensemble learning method has a considerably corrective effect and the three methods(Random Forest,AdaBoost,and Bagging)adopted in the study had similar results.The mean bias between CMPAS and 85%of automatic weather stations has dropped by more than 30%.The plateau region displays the largest accuracy increase,the winter season shows the greatest error reduction,and decreasing precipitation improves the correction outcome.Additionally,the heavy precipitation process’precision has improved to some degree.For individual stations,the revised CMPAS error fluctuation range is significantly reduced.

关键词： machine learning models ensemble learning precipitation correction error correction high-resolution precipitation complex terrain

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A Case Study of the Initiation of Parallel Convective Lines Back-Building from the South Side of a Mei-yu Front over complex terrain

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Advances in Atmospheric Sciences 2021年第5期38卷 717-736页

作者： Qiwei WANG Yi ZHANG Kefeng ZHU Zhemin TAN Ming XUE Key Laboratory of Mesoscale Severe Weather and School of Atmospheric Sciences Nanjing UniversityNanjing 210023China Center for Analysis and Prediction of Storms and School of Meteorology University of OklahomaNormanOK 73072USA

Parallel back-building convective lines are often observed extending to the southwest of some mesoscale convective systems(MCSs)embedded in the mei-yu front in China.The convective lines with echo training behavior can quickly develop into a stronger convective group of echoes,resulting in locally heavy rainfall within the mei-yu front rainband.The initiation mechanism of the back-building convective lines is still unclear and is studied based on high-resolution numerical simulation of a case that occurred during 27−28 June 2013.In the present case,the new convection along the convective lines was found to be forced by nonuniform interaction between the cold outflow associated with the mei-yu front MCSs and the warm southerly airflow on the south side of the mei-yu front,which both are modified by local terrain.The mei-yu front MCSs evolved from the western to the eastern side of a basin surrounded by several mesoscale mountains and induced cold outflow centered over the eastern part of the basin.The strong southwest airflow ahead of the mei-yu front passed the Nanling Mountains and impacted the cold outflow within the basin.The nonuniform interaction led to the first stage of parallel convective line formation,in which the low mountains along the boundary of the two airflows enhanced the heterogeneity of their interaction.Subsequently,the convective group quickly developed from the first stage convective lines resulted in apparent precipitation cooling that enhanced the cold outflow and made the cold outflow a sharp southward windshift.The enhanced cold outflow pushed the warm southerly airflow southward and impacted the mountains on the southeast side of the basin,where the roughly parallel mountain valleys or gaps play a controlling role in a second stage formation of parallel convective lines.

关键词： back-building convective line convective initiation complex terrain mei-yu front

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VALIDATION OF NEAR-SURFACE WINDS OBTAINED BY A HYBRID WRF/CALMET MODELING SYSTEM OVER A COASTAL ISLAND WITH complex terrain

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Journal of Tropical Meteorology 2012年第3期18卷 284-296页

作者：路屹雄汤剑平王元宋丽莉 School of Atmospheric Sciences Nanjing University Climate Center of Guangdong Province

The results from a hybrid approach that combines a mesoscale meteorological model with a diagnostic model to produce high-resolution wind fields in complex coastal topography are evaluated.The diagnostic wind model(California Meteorological Model,CALMET) with 100-m horizontal spacing was driven with outputs from the Weather Research and Forecasting(WRF) model to obtain near-surface winds for the 1-year period from 12 September 2003 to 11 September 2004.Results were compared with wind observations at four sites.Traditional statistical scores,including correlation coefficients,standard deviations(SDs) and mean absolute errors(MAEs),indicate that the wind estimates from the WRF/CALMET modeling system are produced reasonably well.The correlation coefficients are relatively large,ranging from 0.5 to 0.7 for the zonal wind component and from 0.75 to 0.85 for the meridional wind component.MAEs for wind speed range from 1.5 to 2.0 m s-1 at 10 meters above ground level(AGL) and from 2.0 to 2.5 m s-1 at 60 m AGL.MAEs for wind direction range from 30 to 40 degrees at both levels.A spectral decomposition of the time series of wind speed shows positive impacts of CALMET in improving the mesoscale winds.Moreover,combining the CALMET model with WRF significantly improves the spatial variability of the simulated wind fields.It can be concluded that the WRF/CALMET modeling system is capable of providing a detailed near-surface wind field,but the physics in the diagnostic CALMET model needs to be further improved.

关键词： near-surface winds WRF/CALMET modeling system complex terrain

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Fine scale optical remote sensing experiment of mixed stand over complex terrain(FOREST)in the Genhe Reserve Area:objective,observation and a case study

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International Journal of Digital Earth 2021年第10期14卷 1411-1432页

作者： Biao Cao Jianbo Qi Erxue Chen Qing Xiao Qinhuo Liu Zengyuan Li State Key Laboratory of Remote Sensing Science Aerospace Information Research InstituteChinese Academy of SciencesBeijingPeople’s Republic of China State Forestry and Grassland Administration Key Laboratory of Forest Resources and Environmental Management Beijing Forestry UniversityBeijingPeople’s Republic of China Research Institute of Forest Resource Information Techniques Chinese Academy of ForestryBeijingPeople’s Republic of China University of Chinese Academy of Sciences BeijingPeople’s Republic of China

Optical remote sensing allows to efficiently monitor forest ecosystems at regional and global scales.However,most of the widely used optical forward models and backward estimation methods are only suitable for forest canopies in flat areas.To evaluate the recent progress in forest remote sensing over complex terrain,a satellite-airborne-ground synchronous Fine scale Optical Remote sensing Experiment of mixed Stand over complex terrain(FOREST)was conducted over a 1 km×1 km key experiment area(KEA)located in the Genhe Reserve Areain 2016.Twenty 30 m×30 m elementary sampling units(ESUs)were established to represent the spatiotemporal variations of the KEA.Structural and spectral parameters were simultaneously measured for each ESU.As a case study,we first built two 3D scenes of the KEA with individual-tree and voxel-based approaches,and then simulated the canopy reflectance using the LargE-Scale remote sensing data and image Simulation framework over heterogeneous 3D scenes(LESS).The correlation coefficient between the LESS-simulated reflectance and the airborne-measured reflectance reaches 0.68-0.73 in the red band and 0.56-0.59 in the near-infrared band,indicating a good quality of the experiment dataset.More validation studies of the related forward models and retrieval methods will be done.

关键词： Remote sensing experiment forest complex terrain Genhe Reserve Area LESS

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Simulation analysis of environmental risk accident and management of high-sulfur gas field development in complex terrain

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Frontiers of Environmental Science & Engineering 2008年第3期2卷 318-325页

作者： Xiao WANG Fanghua HAO Xuan ZHANG Wen SUN Hongguang CHENG State Key Laboratory of Water Environment Simulation School of EnvironmentBeijing Normal UniversityBeijing 100875China

Environmental risk of high sulfur gas field exploitation has become one of the hot spots of environmental management studies.Severe gas H_(2)S blowout accidents in recent years have shown that poor understanding and estimates of the poisonous gas movement could lead to dangerous evacuation delays.It is important to evaluate the real concentration of H_(2)S,especially in complex terrain.Traditional experiential models are not valid in the case of rough terrain,especially in low-lying areas where the gas accumulates.This study,using high sulfur content gas field of Sichuan“Pu Guang gas field”as study object and adopting objective diagnosis of wind field of land following coordinate three dimensions,applied Lagrangian Puff Model and breaking up technique of puffs to simulate the H_(2)S diffusion condition of blowout accidents produced in the high sulfur content gas field of complex terrain area.The results showed that the H_(2)S distribution did not occur mainly in low wind direction,and due to the obstruction of the mountain’s body,it accumulated in front of mountain on produced turn over,flowed around submitted jumping type distribution.The mountain waist near the hilltop and low hollow river valley site rapture points simulating contrast showed that the higher the rapture point,the better the diffusing condition of pollutant,the distribution of risk sensitive point decided piping rupture environmental risk size combining the H_(2)S diffusion result and residential area dispersing in the study area,synthetic judge located in the high rapture point environmental risk was smaller than the low hollow point,thus it was suggested to carryout laying of lining build of equal high line of higher terrain.According to simulation results,the environmental risk management measures aimed at putting down adverse effects were worked out.

关键词： complex terrain high-sulfur gas field environmental risk accident Lagrangian Puff Model

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3D MODEL STUDY ON FOG OVER complex terrain—PART Ⅱ:NUMERICAL EXPERIMENT

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Acta meteorologica Sinica 1997年第1期11卷 88-94页

作者：李子华石春娥陆韬实 Nanjing Institute of Meteorology Nanjing 210044 Liaoning Bureau of Meteorology Shenyang 110001

A series of numerical sensitivity experiments on Chongqing fog are made using the 3D fog model over complex terrain.Some factors affecting Chongqing fog are studied.

关键词： Chongqing fog complex terrain numerical experiment

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NUMERICAL STUDY ON THE LOCAL WIND STRUCTURES FORCED BY THE complex terrain OF QINGDAO AREA

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Acta meteorologica Sinica 1992年第3期6卷 355-366页

作者：吴增茂 K.HeinkeSchlunzen Institute of Physical Oceanography Ocean University of QingdaoQingdao 266003 Meteorological Institute University of Hamburg2000 Hamburg 13F.R.G.

In this paper, some 2-D features of the down- and up-slope winds and sea-land-breeze generated over the com- plex terrain of the Qingdao area and the interaction between them are numerically analysed by use of a 2-D non-hydrostatic mesoscale model. The simulated results in the west-east vertical cross-section show that (1) when the large-scale wind is a southerly gentle one, the generated easterly down-slope wind is much stronger than with an oppo- site background wind, and the down-slope wind can trigger and intensify the land breeze corresponding to the eastern coast of Jiaozhou Bay; (2) a gentle westerly background wind will reduce the eastward sea breeze and up-slope wind during the daytime due to a cold advection, but shows a little effect on the mesoscale circulation formed in the nighttime.

关键词： numerical study local wind structure complex terrain Qingdao area

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3D MODEL STUDY ON FOG OVER complex terrain—PART Ⅰ:NUMERICAL STUDY

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Acta meteorologica Sinica 1996年第4期10卷 493-506页

作者：石春娥孙学金杨军李子华 Nanjing Institute of Meteorology Nanjing 210044

A three-dimensional fog model,suitable for precipitous and complex terrain,is designed contain- ing four prognostic variables—wind speed,potential temperature,specific humidity and mixing ratio of liquid water.The model considers turbulent exchange,the long-wave radiation on the ground sur- face and in the air.the short-wave solar radiation,the evaporation and condensation of moisture and the surface heat budget and so on.In order to make the model run steadily on precipitous and complex terrain,we have improved the method of calculating horizontal pressure gradient force in the terrain coordinate system.The results coincide on the whole with the actual situation.

关键词： Chongqing fog 3D model complex terrain urban heat island

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Computational fluid dynamics simulation of gas dispersion in complex facilities using Kit Fox field experiments:Validation and statistical evaluation

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Chinese Journal of Chemical Engineering 2022年第4期35卷 412-423页

作者： Narjes Hemati Alam Eslam Kashi Razieh Habibpour Department of Chemical Technologies Iranian Research Organization for Science and TechnologyP.O.Box 33535111TehranIran

Gas release and its dispersion is a major concern in chemical industries.In order to manage and mitigate the risk of gas dispersion and its consequences,it is necessary to predict gas dispersion behavior and its concentration at various locations upon emission.Therefore,models and commercial packages such as Phast and ALOHA have been developed.Computational fluid dynamics(CFD)can be a useful tool to simulate gas dispersion in complex areas and conditions.The validation of the models requires the employment of the experimental data from filed and wind tunnel experiments.It appears that the use of the experimental data to validate the CFD method that only includes certain monitor points and not the entire domain can lead to unreliable results for the intended areas of concern.In this work,some of the trials of the Kit Fox field experiment,which provided a wide-range database for gas dispersion,were simulated by CFD.Various scenarios were considered with different mesh sizes,physical conditions,and types of release.The results of the simulations were surveyed in the whole domain.The data matching each scenario was varied by the influence of the dominant displacement force(wind or diffusivity).Furthermore,the statistical parameters suggested for the heavy gas dispersion showed a dependency on the lower band of gas concentration.Therefore,they should be used with precaution.Finally,the results and computation cost of the simulation could be affected by the chosen scenario,the location of the intended points,and the release type.

关键词： Gas dispersion simulation Computational fluid dynamics complex terrain Obstructed flow

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