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Discrete element simulation of crushable rockfill materials

Water Science and Engineering 2013年第2期6卷 215-229页

作者： Lei SHAO Shi-chun CHI Liang-jing ZHOU Yu-zan WANG Faculty of Infrastructure Engineering Dalian University of Technology Hydrochina Chengdu Engineering Corporation Changjiang institute of survey Planning Design and Research Changjiang Water Resources Commission

A discrete element method was used to study the evolution of particle crushing in a rockfill sample subjected to triaxial shear. A simple procedure was developed to generate clusters with arbitrary shapes, which resembled real rockfill particles. A theoretical method was developed to define the failure criterion for an individual particle subjected to an arbitrary set of contact forces. Then, a series of numerical tests of large-scale drained triaxial tests were conducted to simulate the behaviors of the rockfill sample. Finally, we examined the development of micro-characteristics such as particle crushing, contact characteristics, porosity, deformation, movement, and energy dissipation. The simulation results were partially compared with the laboratory experiments, and good agreement was achieved, demonstrating that the particle crushing model proposed can be used to simulate the drained triaxial test ofrockfill materials. Based on a comparison of macro behaviors of the roekfill sample and micro structures of the particles, the microscopic mechanism of the rockfill materials subjected to triaxial shear was determined qualitatively. It is shown that the crushing rate, rather than the number of crushed particles, can be used to reflect the relationship between macro- and micro-mechanical characteristics of rockfill materials. These research results further develop our understanding of the deformation mechanism of rockfill materials.

关键词： discrete element simulation triaxial shear test," roclcfill material geometric construction of particles particle flow code microscopic mechanism

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An enhanced method for estimating snow water equivalent in the central part of the Tibetan Plateau using raster segmentation and eigenvector spatial filtering regression model

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Journal of Mountain Science 2022年第9期19卷 2570-2586页

作者： CHENG Qi-shan CHEN Yu-min YANG Jia-xin CHEN Yue-jun XIONG Zhe-xin ZHOU An-nan School of Resource and Environment Science Wuhan UniversityWuhan 430079China Guangzhou Urban Planning&Design survey research institute Guangzhou 510060China

Snow water equivalent(SWE)is an important factor reflecting the variability of *** is important to estimate SWE based on remote sensing data while taking spatial autocorrelation into *** on the segmentation method,the relationship between SWE and environmental factors in the central part of the Tibetan Plateau was explored using the eigenvector spatial filtering(ESF)regression model,and the influence of different factors on the SWE was *** sizes of 16×16,24×24 and 32×32 were selected to segment raster datasets into *** eigenvectors of the spatial adjacency matrix of the segmented size were selected to be added into the model as spatial factors,and the ESF regression model was constructed for each block in *** show that precipitation has a great influence on SWE,while surface temperature and NDVI have little *** temperature,elevation and surface temperature have completely different effects in different *** with the ordinary least square(OLS)linear regression model,geographically weighted regression(GWR)model,spatial lag model(SLM)and spatial error model(SEM),ESF model can eliminate spatial autocorrelation with the highest *** the segmentation size increases,the complexity of ESF model increases,but the accuracy is improved.

关键词： Snow water equivalent Tibetan Plateau Raster segmentation Parallel eigenvector spatial filtering

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Centrifuge model test of an irrigation-induced loess landslide in the Heifangtai loess platform, Northwest China

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Journal of Mountain Science 2018年第1期15卷 130-143页

作者： CUI Sheng-hua PEI Xiang-jun WU Hao-yu HUANG Run-qiu State Key Laboratory of Geohazard Prevention and Geoenvironment Protection Chengdu University of Technology Sichuan Provincial Transport Department Highway Planning Survey Design and Research Institute

The Heifangtai platform in Northwest China is famous for irrigation-induced loess *** study conducted a centrifuge model test with reference to an irrigation-induced loess landslide that occurred in Heifangtai in *** loess slope model was constructed by whittling a cubic loess block obtaining from the landslide *** irrigation water was simulated by applying continuous infiltration from back of the *** deformation,earth pressure,and pore pressure were investigated during test by a series of *** this particular study,the results showed that the failure processes were characterized by retrogressive landslides and *** time dependent reductions of cohesion and internal friction angle at basal layer with increasing pore-water pressure were responsible for these *** foot part of slope is very important for slope instability and hazard prevention in the study area,where concentration of earth pressure and generation of high pore-water pressures would form before *** measurements of earth pressure and pore-water pressure might be effective for early warning in the study area.

关键词： Irrigation-induced landslide Centrifuge model test Early warning Pore pressure Earth pressure

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Breaches of the Baige Barrier Lake: Emergency response and dam breach flood

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Science China(Technological Sciences) 2020年第7期63卷 1164-1176页

作者： CAI YaoJun CHENG HaiYun WU ShuaiFeng YANG QiGui WANG Lin LUAN YueSheng CHEN ZuYu Changjiang institute of survey PlanningDesign and ResearchWuhan 430010China Bureau of Hydrology Changjiang Water Resource CommissionWuhan 430010China State Key Laboratory'of Simulation and Regulation of Water Cycle in River Basin.China institute of Water Resources and Hydropower research Beijing 100038China Department of geotechnical Engineering China Institute of Water Resources and Hydropower ResearchBeijing 100048China State Key Laboratory of Eco-hydraulics in Northwest Arid Region Xi'an University of Technology'Xi'an 710048China Changjiang survey institute of MWR Wuhan 430011China

This paper documents the emergency response to the breaches of the Baige Barrier Lake. The lake was successively formed by landslides that occurred on October 10 and November 3, 2018 at the provincial border between Sichuan and Tibet in China. The barrier lake created by the "10.10" landslide breached on October 12 and triggered a flood with a peak discharge around 10000 m^3/s. The residual landslide barrier was enhanced by a second landslide on November 3, resulting in a higher barrier with larger flood potential. An overflow channel was excavated in the crest of the barrier to prompt the breach to be triggered at a lower water level. The second breach happened on November 12 with a measured peak discharge of 31000 m^3/s. Nearly 75000 people were evacuated before the two breaches. In order to prevent the downstream dams from possible over-topping, nearly 3.27×10~8 m^3 of the stored volume was released from the Liyuan reservoir 688 km downstream of Baige Barrier Lake. This paper presents the measured hydrographs and the back-analysis results for the "11.03" barrier lake. It is shown that the modern models of dam breach hydraulics can reasonably reproduce the barrier breach hydrographs;however, further studies are needed to define the key parameters which highly influence the calculated results. Knowledge acquired during the emergency response to the case can be shared with experts working on breaches of embankment dams and can be referenced to promote both the theory study and the engineering practice to mitigate the potential risks caused by this type of catastrophic events.

关键词： dam breach back analysis baige barrier lake emergency response downstream flood propagation

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The Cu-Mo Mineralization of the Late Jurassic Porphyry in the Northern Great Xing'an Range: Constraints from Zircon U-Pb Ages of the Ore-Causative Granites

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Acta Geologica Sinica(English Edition) 2019年第1期93卷 236-237页

作者： DENG Changzhou LI Guanghui College of Earth Sciences Jilin University Heilongjiang institute of Geological survey

The Great Xing’an Range(GXAR)is one of the most important metallogenic belts in *** study has shown that porphyry Cu-Mo deposit distributed in the northern Great Xing’an Range formed mainly in two stages:(1)Early Ordovician,such as Duobaoshan and Tongshan deposits(Liu et al.,2017);2)Triassic-Early Jurassic,including Wunugetushan,Taipingchuan and Badaguan deposits(Tang et al.,2016).In recent years,two potential porphyry Cu-Mo deposits,Huoluotai and Xiaokele,were discovered in the Erguna Block,northern GXAR(Figs.1a–b).However,the ore formation ages and regional metallogenic regularity are ambiguous due to the lack of isotopic *** zircon U-Pb ages from the ore-causative granites were reported in this paper,with the aims to constrain the metallogenic ages and provide evidence for study of the regional metallogenic regularity and ore prospect prediction.

关键词： The Great Xing’an Range(GXAR) granites Cu-Mo

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Theory and practice concerning classification for expansive soils using standard moisture absorption water content

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Science China(Technological Sciences) 2005年第1期48卷 31-40页

作者： YAO Hailin1, CHENG Ping2, YANG Yang1 & WU Wanping2 1. institute of Rock and Soil Mechanics, Chinese Academy of Sciences, Wuhan 430071, China 2. China Communications Second Highway survey Design and research institute, Wuhan 430052, China 1. institute of Rock and Soil Mechanics Chinese Academy of Sciences 430071 Wuhan China 2. China Communications Second Highway survey Design and research institute 430052 Wuhan China

A series of tests on physical, mechanical and chemical properties of expansive soils have shown that the standard moisture absorption water content (SMA) of expansive soils has a good linear relationship with montmorillonite content, cation exchange capacity, specific surface, and it also presents a linear relationship tendency to plastic index and free swell ratio. All this indicates that the above SMA is of clear significance in physics. The plastic index can better reflect the interaction extent between composition and dispersing character of grains, cation and clay minerals. Consequently, SMA can reflect the basic essential properties of expansive soils. On the basis of the classification results that have been published in literature and in consideration of the succession to the classification results for the free swell ratio, this paper puts forward three indexes, i.e. the SMA, plastic index and free swell ratio to classify expansive soils. The tests proposed for the classification indexes are easy to operate, simple in testing device and last a short time. Compared with the latest issued “Classification Standard Code for Rocks and Soils of Railway Projects” (TB10077-2001), the method proposed in this paper is more convenient and reasonable, and can be popularized, when environment conditions ripen, for the application in field of exploration and design of highway in the areas surrounded by expansive soils.

关键词： expansive soil, standard moisture absorption water content (SMA), plasticity index, free expansive ratio, identification and classification of expansive soils.

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Characteristics and dynamic analysis of the February 2021 long-runout disaster chain triggered by massive rock and ice avalanche at Chamoli, Indian Himalaya

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Journal of Rock Mechanics and geotechnical Engineering 2023年第2期15卷 296-308页

作者： Tiantian Zhang Yueping Yin Bin Li Xiaojie Liu Meng Wang Yang Gao Jiawei Wan Kaushal Raj Gnyawali institute of Geomechanics Chinese Academy of Geological SciencesBeijing100081China China institute of Geological Environment Monitoring China Geological SurveyBeijing100081China College of Geology Engineering and Geomatics Chang’an UniversityXi’an710100China Sichuan Geological survey institute Chengdu610081China Natural Hazards Section Himalayan Risk Research Institute(HRI)Bhaktapur44800Nepal

A massive rock and ice avalanche occurred on the western slope of the Ronti Gad valley in the northern part of Chamoli,Indian Himalaya,on 7 February 7,*** avalanche on the high mountain slope at an elevation of 5600 m above sea level triggered a long runout disaster chain,including rock mass avalanche,debris avalanche,and *** disaster chain had a horizontal travel distance of larger than 17,600 m and an elevation difference of 4300 *** this study,the disaster characteristics and dynamic process were analyzed by multitemporal satellite *** results show that the massive rock and ice avalanche was caused by four large expanding discontinuity *** disaster chain was divided into five zones by satellite images and field observation,including source zone,transition zone,dynamic entrainment zone,flow deposition zone,and flood *** entrainment effect and melting water were recognized as the main causes of the long-runout *** on the seismic wave records and field videos,the time progress of the disaster was analyzed and the velocity of frontal debris at different stages was *** total analyzed disaster duration was 1247 s,and the frontal debris velocity colliding with the second hydropower station was approximately 23 m/*** study also carried out the numerical simulation of the disaster by rapid mass movement simulation(RAMMS).The numerical results reproduced the dynamic process of the debris avalanche,and the mechanism of long-runout avalanche was further verified by parametric ***,this study discussed the potential causes of disaster and flood and the roles of satellite images and seismic networks in the monitoring and early-warning.

关键词： Rock and ice avalanche Disaster chain Long-runout Entrainment Flood

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Cluster and characteristic analysis of Shanghai metro stations based on metro card and land-use data

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Geo-Spatial Information Science 2020年第4期23卷 352-361页

作者： Ping Shen Linxin Ouyang Chong Wang Yin Shi Yiheng Su Guangzhou Urban Planning&Design survey research institute GuangzhouChina Shanghai Tongji Urban Planning&Design institute Co. Ltd.ShanghaiChina Tongji Architectural Design(Group)Co. Ltd.ShanghaiChina Shanghai Urban Planning and Design research institute ShanghaiChina

Metro is an important form of public transport in *** on the metro card data,we conduct the cluster analysis of Shanghai metro stations according to the pattern of passenger flow changing with *** the characteristics of travel time and surrounding land use are investigated for different types of stations to explore the relationship between urban land-use characteristics and travel activities reflected by passenger flow at metro *** is found that the passenger flow pattern of metro stations is closely related to the location conditions of stations and its surrounding land-use *** on various characteristics,285 metro stations are classified into four types,including residential-oriented stations,employmentoriented stations,employment-residence-oriented stations,and integrated functionaloriented stations,reflecting the interaction between spontaneous travel behavior and urban land-use characteristics and providing a reference for optimizing the urban functional structure and the spatial allocation of facilities.

关键词： Metro stations travel behavior pattern metro card data land use

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Size structure of biomass and primary production of phytoplankton：environmental impact analysis in the Dongsha natural gas hydrate zone, northern South China Sea

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Acta Oceanologica Sinica 2018年第1期37卷 97-107页

作者： KANG Jianhua LIANG Qianyong WANG Jianjun LIN Yili HE Xuebao XIA Zhen ZHENG Xinqing WANG Yu Third institute of Oceanography State Oceanic Administration Xiamen 361005 China Guangzhou Marine Geological survey China Geological Survey Guangzhou 510760 China

The size-fractionated biomass and primary production of phytoplankton, and the influence of environmental factors on it were studied in the Dongsha natural gas hydrate zone of the northern South China Sea in May *** nutrient, low chlorophyll a（Chl a） and primary productivity characteristics were found in these waters. The phenomena of subsurface Chl a maximum layers（SCMLs） and primary production maximum layers（SPMLs）were observed in the Dongsha waters. There were significant differences in the size-fractionated biomass and primary production that showed picophytoplankton〉nanophytoplankton〉microphytoplankton in terms of biomass and degree of contribution to production. Vertical biomass distribution indicated there were considerable differences among different phytoplankton within the euphotic zone（Zeu） in spring. For example,microphytoplankton was distributed evenly in the euphotic layer and nanophytoplankton was mainly distributed in the subsurface or in the middle of the euphotic layer, while picophytoplankton was mainly distributed in the middle or bottom of the euphotic layer. Smaller cell size and larger relative surface area allow picophytoplankton to benefit from nutrient competition and to hold a dominant position in the tropical oligotrophic waters of low latitudes. There was a positive correlation between size-fractionated biomass and temperature with pH and a negative correlation between size-fractionated biomass and silicate with phosphate. There was a positive correlation between size-fractionated primary production and temperature and a negative correlation between size-fractionated biomass and salinity with phosphate. Phosphate was an important factor influencing the size structure of phytoplankton. Meanwhile, irradiation and the euphotic layer were more important in regulating the vertical distribution of size-fractionated phytoplankton in the Dongsha natural gas hydrate zone.

关键词： phytoplankton biomass primary production size fractionation gas hydrate northern South China Sea

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Texture development of mesophase in reservoir pyrobitumen and the temperature-pressure converting of the gas reservoir in the Chuanzhong Uplift, Southwestern China

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Petroleum Science 2023年第2期20卷 721-732页

作者： Cheng-Yu Yang Mei-Jun Li Tie-Guan Wang Ning-Ning Zhong Rong-Hui Fang Long Wen State Key Laboratory of Petroleum Resources and Prospecting China University of PetroleumBeijing102249China Oil&Gas survey China Geological SurveyBeijing100083China The Key Laboratory of Unconventional Petroleum Geology China Geological SurveyBeijing100083China Exploration and Development research institute of Southwest Oil&Gasfield Company PetroChinaChengduSichuan610041China

The Neoproterozoic-Lower Paleozoic dolostone gas reservoirs in the Chuanzhong Uplift in Southwestern China contain the mesophase pyrobitumen (pyrobitumen with mesophase). The mesophase in the pyrobitumen is mostly composed of a mixture of condensed macromolecule polycyclic aromatic hydrocarbons (PAH), and has been mostly converted to various grain, flow, and domain textures. The volcanic activity nearby the Chuanzhong Uplift may have generated very hot (over 300 °C) hydrothermal fluid, with migration of the fluid into the dolostone reservoir transforming the hydrocarbons in the reservoir into an anisotropic carbon by-product, which formed under high temperature and pressure conditions;over 300 °C and 200 MPa according to fluid inclusion analysis. The high temperature-pressure in reservoir was caused by sudden devolatilization of the hydrocarbons due to hydrothermal heating, which formed the unusual texture of the mesophase. The elliptical mesophase grains (EG), the honeycomb structure of pyrobitumen, and the occurrence of polarized classes of mesophase in single pyrobitumen deposits are all unusual textures. This study investigates the texture development of this pressure-affected pyrobitumen. Observation and study of the mesophase suggest that the class of mesophase in pyrobitumen is determined by temperature, while pressure (assessed from associated fluid inclusions) significantly affected the texture. Analysis of the texture of the pyrobitumen in conjunction with previous thermometry results from methane inclusions suggests that the high class mesophase of the pyrobitumen could be applied as a temperature indicator for geological conditions. Furthermore, the unusual textures of the pyrobitumen including elliptical mesophase grains (EG), the honeycomb structure of pyrobitumen, and the occurrence of polarized classes of mesophase in single pyrobitumen could reflect the abnormal high formation pressure.

关键词： Pyrobitumen Mesophase Optical texture Pressure affect Oil reservoir Chuanzhong Uplift

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