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A nonlinear interface structural damage model between ice crystal and frozen clay soil

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Research in Cold and Arid Regions 2021年第2期13卷 150-166页

作者： Sheng Shi Feng Zhang KangWei Tang DeCheng Feng XuFeng Lu School of Transportation Science and engineering Harbin Institute of TechnologyHeilongjiangHarbin 150090China state key {2. of Road engineering Safety and Health in Cold and High−Altitude Regions CCCC First Highway Consultants Co.Ltd.Xi'an 710075China

The shear properties of ice-frozen soil interface are important when studying the constitutive model of frozen soil and slope stability in cold regions. In this research, a series of cryogenic direct shear tests for ice-frozen clay soil interface were conducted. Based on experimental results, a nonlinear interface structural damage model is proposed to describe the shear properties of ice-frozen clay soil interface. Firstly, the cementation and friction structural properties of frozen soil materials were analyzed, and a structural parameter of the ice-frozen clay soil interface is proposed based on the cryogenic direct shear test results. Secondly, a structural coefficient ratio is proposed to describe the structural development degree of ice-frozen clay soil interface under load, which is able to normalize the shear stress of ice-frozen clay soil interface,and the normalized data can be described by the Duncan-Chang model. Finally, the tangent stiffness of ice-frozen clay soil interface is calculated, which can be applied to the mechanics analysis of frozen soil. Also, the shear stress of ice-frozen clay soil interface calculated by the proposed model is compared with test results.

关键词： ice-frozen clay soil interface cryogenic direct shear test structural coefficient ratio shear tangent stiffness cementation

Impacts of climate-induced permafrost degradation on vegetation:A review

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Advances in Climate Change Research 2021年第1期12卷 29-47页

作者： JIN Xiao-Ying JIN Hui-Juna Go IWAHANA Sergey SMARCHENKO LUO Dong-Liang LI Xiao-Ying LIANG Si-Hai Northeast-China Observatory and Research Station of Permafrost Geological Environment(Ministry of Education) School of Civil EngineeringInstitute of Cold Region Science and TechnologyNortheast Forestry UniversityHarbin150040China state key {2. of frozen Soils engineering Northwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhou730000China College of Resources and Environment University of Chinese Academy of SciencesBeijing100049China International Arctic Research Center University of Alaska FairbanksFairbanks99775USA Permafrost Lab Geophysical InstituteUniversity of Alaska FairbanksFairbanks99775USA School of Water Resources and Environment China University of GeosciencesBeijing100083China

Under a warming climate,degrading permafrost profoundly and extensively affects arctic and alpine ***,most existing relevant studies are more focused on the hydrothermal impacts of vegetation on the underlying permafrost,or symbiosis between vegetation and permafrost,only very few on ecological impacts of permafrost ***,there are much more pertinent investigations in arctic and boreal regions than those in alpine and high-plateau regions at mid-and low *** study emphasizes on the impact mechanisms of permafrost degradation on vegetation both at high and mid-to low latitudes,addressing vegetation succession trajectories and associated changes in soil hydrology and soil nutrient above degrading *** degradation influences vegetation by altering soil hydrology,soil biogeochemical processes and microbial communities,which further improve soil nutrient ***,under a warming climate,vegetation may take two successional trajectories,towards a wetter or drier ecosystem within a certain time period,but to a drier ecosystem in the end upon the thaw of permafrost in case of permeable soils and good ***,with rapidly developing remote-sensing and other space-and ground-based and air-borne observational networks and numerical predictive models,the impacting mechanisms of permafrost degradation on vegetation should be timely and better monitored,evaluated and modeled at desired spatiotemporal scales and resolutions by terrestrial or integrated ecosystem models.

关键词： Degrading permafrost Vegetation Impact mechanisms Climate warming Ecological impacts

"Nonlinear" characteristics of the static earth pressure coefficient in thick alluvium

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Mining Science and Technology 2009年第1期19卷 129-132页

作者： XU Zhi-wei ZENG Kai-hua WEI Zhou LIU Zhi-qiang ZHAO Xiao-dong TIAN Qiu-hong state key {2. for Geomechanics ＆ Deep Underground engineering School of Architecture and Civil Engineering China University of Mining ＆ Technology Xuzhou Jiangsu 221008 China Nanchang Institute of Technology Nanchang Jiangxi 330099 China Jiangsu Tiandi Steel Structure Work engineering Group Co. Ltd. Xuzhou Jiangsu 221006 China

Exact calculations of the static earth pressure from a thick alluvium require accurate/Co values. These calculations influence the sinking cost and the safety of the freezing method. The static earth pressure coefficient （K0） of thick and deep soil was analyzed using laboratory tests. The results show that the static earth pressure coefficient of thick and deep soils is nonlinear and different from that of superficial soils. The constant of superficial soils is usually invariant and the total stress or incremental stress definitions used in traditional geo-meehanics give the same value. The influence of load increments when calculating for superficial soil is ignored. The difference in values of K0 for thick alluvium defimed by the total stress or the incremental stress methods is over 10%. The effects of the thick alluvium on K0 should be considered during the design of frozen shaft projects. Such things as the frozen shaft thickness and the excavated section height should be chosen to assure the rationality of the design and to avoid potential faults and accidents.

关键词： thick alluvium static earth pressure coefficient nonlinear analysis

Freeze-thaw processes of active-layer soils in the Nanweng'he River National Natural Reserve in the Da Xing'anling Mountains,northern Northeast China

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Research in Cold and Arid Regions 2018年第2期10卷 104-113页

作者： RuiXia He HuiJun Jin XiaoLi Chang YongPing Wang LiZhong Wang state key {2. of frozen Soil engineering Northwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhouGansu 730000China School of Civil engineering Harbin Institute of TechnologyHarbinHeilongjiang 150090China Hunan University of Science and Technology XiangtanHunan 411201China School of Civil engineering North University of NationalitiesYinchuanNingxia 750030China Nenjiangyuan Forest Ecosystem Research Station Institute of Agriculture and ForestryDa Xing'anling Forestry GroupJiagedaqiHeilongjiang 165000China

The active-layer soils overlying the permafrost are the most thermodynamically active zone of rock or soil and play important roles in the earth-atmosphere energy system. The processes of thawing and freezing and their associated complex hydrothermal coupling can significantly affect variation in mean annual temperatures and the formation of ground ice in permafrost regions. Using soil-temperature and-moisture data obtained from the active layer between September 2.11 and October 2.14 in the permafrost region of the Nanweng'he River in the Da Xing'anling Mountains, the freeze-thaw characteristics of the permafrost were studied. Based on analysis of ground-temperature variation and hydrothermal transport characteristics, the thawing and freezing processes of the active layer were divided into three stages:(1) autumn-winter freezing,(2. winter freeze-up, and(3) spring-summer thawing. Variations in the soil temperature and moisture were analyzed during each stage of the freeze-thaw process, and the effects of the soil moisture and ground vegetation on the freeze-thaw are discussed in this paper. The study's results show that thawing in the active layer was unidirectional, while the ground freezing was bidirectional(upward from the bottom of the active layer and downward from the ground surface).During the annual freeze-thaw cycle, the migration of soil moisture had different characteristics at different stages. In general, during a freezing-thawing cycle, the soil-water molecules migrate downward, i.e., soil moisture transports from the entire active layer to the upper limit of the permafrost. In the meantime, freeze-thaw in the active layer can be significantly affected by the soil-moisture content and vegetation.

关键词： Nanweng'he River National Natural Reserve active layer freeze-thawing processes moisture content vegetation effect

Numerical evaluation of the effectiveness of frost heave mitigation strategies for chilled arctic gas pipelines

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Research in Cold and Arid Regions 2022年第5期14卷 338-345页

作者： XinZe Li QingBai Wu HuiJun Jin Rui Shi Gang Wu YaPeng Cao state key {2. of frozen Soils engineering Northwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhouGansu 730000China College of Resources and Environment University of Chinese Academy of SciencesBeijing 100049China Department of Chemical and Material engineering University of AlbertaEdmontonAB T6G1H9Canada School of Civil engineering/Northeast-China Observatory and Research-Station of Permafrost Geo-Environment–Ministry of Education/Institute of Cold-Regions engineering Science and TechnologyNortheast Forestry UniversityHarbinHeilongjiang 150040China Department of Oil&Gas Storage and Transportation engineering School of EngineeringChina University of Petroleum-Beijing at KaramayXinjiang Uygur Autonomous Region 834000China

To prevent the thawing of ice-rich permafrost,it is suggested that gas should be transported in a chilled state(below the freezing temperature)in pipelines buried in ***,frost heave occurs when water migrates towards the chilled pipeline and ice lenses grow underneath the *** might endanger the integrity of the pipeline and the environment as ***,innovative frost heave mitigation measures are required when designing the pipeline,especially those sections in discontinuous permafrost or near the compressor sta*** ground temperature field in response to the operation of a proposed chilled gas pipeline traversing permafrost regions in Alaska was simulated by a pipe-soil thermal interaction geothermal *** heave mitigation measures,including insulation around the pipe,flat slab insulation under the pipe,and heating cables combined with slab insulation,were evaluated for chilled pipeline operation in seasonally varying ambient *** numerical results show that the minimum temperature of the observation point at 2.5 m below the pipe bottom increases by 17%,2.%,and 48%when the thermal conductivity of the outer insulation layer is 0.1,0.05,and 0.02.W/(m K),*** flat slab insulation,the thermal field is less sensitive to varying slab thicknesses than to varying thermal conductivity,implying the thermal conductivity,not the thickness,is the crucial ***,the heat flow could be redirected from vertical to horizontal by flat slab *** electrical heating cables could be regarded as a new heat source to balance the heat removal rate of the soil around the chilled *** minimum temperature of the observation point at 1.1 m below the bottom of the pipe increases from-15.2.to-3.0,1.5,and 7.5℃,corresponding to the heating cable power of 2.,30,and 40 W,respectively,with the power of 30 W deemed appropriate for the study *** is concluded that heating cables in combination with insulation

关键词： Permafrost Chilled gas pipeline Temperature field Numerical assessment

Using Path Analysis to Identify the Influence of Climatic Factors on Spring Peak Flow Dominated by Snowmelt in an Alpine Watershed

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Journal of Mountain Science 2014年第4期11卷 990-1000页

作者： ZHANG Fei-Yun LI Lan-Hai AHMAD Sajjad LI Xue-Mei state key {2. of Desert and Oasis Ecology Xinjiang Institute of Ecology and Geography Chinese Academy of Sciences Graduate School University of Chinese Academy of Sciences Department of Civil and Environmental engineering University of Nevada Las Vegas NV 89154-4015 USA Faculty of Geomatics Lanzhou Jiaotong University

Spring snowmelt peak flow （SSPF） can cause serious damage. Precipitation as rainfall directly contributes to the SSPF and influences the characteristics of the SSPF, while temperature indirectly impacts the SSPF by shaping snowmelt rate and determining the soil frozen state which partitions snowmelt water into surface runoff and soil infiltration water in spring. It is necessary to identify the important and significant paths of climatic factors influencing the SSPF and provide estimates of the magnitude and significance of hypothesized causal connections between climatic factors and the SSPF. This study used path analysis with a selection of five factors - the antecedent precipitation index （API）, spring precipitation （SP）, winter precipitation as snowfall （WS）, 〈0℃ temperature accumulation in winter （[ATNI）, and average 〉0℃temperature accumulation in spring （AT） - to analyze their influences on the SSPF in the Kaidu River in Xinjiang, China. The results show that {ATN}, AT and WS have a significant correlation with the SSPF, while API and SP do not show a significant correlation. AT and WS directly influence the SSPF, while as the influence of[ATN] on SSPF is indirect through WS and AT. The indirect influence of [ATN[ on SSPF through WS accounts for 69% of the total influence of [ATN] on SSPF. Compared to the multiple linear regression method, path analysis provides additional valuable information, including influencing paths from independent variables to the dependent variable as well as direct and indirect impacts of external variables on the internal variable. This information can help improve the description of snow melt and spring runoff in hydrologic models as well as the planning and management of water resources.

关键词： Snowmelt Peak flow Path analysis Alpine watershed

Changes in permafrost and snow cover in the Boreal and Arctic zones(BAZs)and their impacts

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Advances in Climate Change Research 2023年第2期14卷 157-163页

作者： Hui-Jun JIN Daqing YANG Olga MAKARIEVA Liang TANG School of Civil engineering|Permafrost Institute Northeast Forestry UniversityHarbin 150040China state key {2. of frozen Soils engineering Northwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhou 730000China Scientific Observation and Research Station of Permafrost and Cold-Regions Environment in the Da Xing'anling Mountains Northeast ChinaNatural Resources Institute of Heilongjiang ProvinceHarbin 150036China Institute of Tibet Plateau Research Chinese Academy of SciencesBeijing 1000101China National Hydrology Research Centre Environment CanadaSaskatoonSaskatchewan S7N 3H5Canada Institute of Earth Sciences St.Petersburg State UniversitySt.Petersburg199034Russia School of Civil engineering Harbin Institute of TechnologyHarbin 150090China

*** Amplified climate warming and wetting have been observed in the Boreal and Arctic zones(BAZs).Due to extensive and persistent warming of the climate and the increasing impacts of human activities,we are seeing degradation of the permafrost and rapid shrinkage of the snow cover in the *** attention has been paid to the reconstruction of past permafrost and monitoring,mapping and evaluation of permafrost and snow cover,and the use of models to predict and evaluate future gradual permafrost *** attention,however,has been given to the rapidly changing permafrost and the associated *** may have led to an underestimation of the rapid changes in the cryolithozone and their effects on the climate,ecosystems,and hydrology systems and on *** particular,natural resources and environmental management in northern countries requires better and more systematic understanding of the history,processes,mechanisms and trends of the northern cryosphere and their environmental and engineering impacts.

关键词： Arctic warming ozone

Numerical Simulation and Analysis of Solid-liquid Two-phase Flow in Centrifugal Pump

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Chinese Journal of Mechanical engineering 2013年第1期26卷 53-60页

作者： ZHANG Yuliang LI Yi CUI Baoling ZHU Zuchao DOU Huashu The state key Lab of Fluid Power Transmission and Control Zhejiang University The Province key Lab of Fluid Transmission Technology Zhejiang Sci-Tech University

The flow with solid-liquid two-phase media inside centrifugal pumps is very complicated and the relevant method for the hydraulic design is still immature so far. There exist two main problems in the operation of the two-phase flow pumps, i.e., low overall efficiency and severe abrasion. In this study, the three-dimensional, steady, incompressible, and turbulent solid-liquid two-phase flows in a low-specific-speed centrifugal pump are numerically simulated and analyzed by using a computational fluid dynamics （CFD） code based on the mixture model of the two-phase flow and the RNG k-~ two-equation turbulence model, in which the influences of rotation and curvature are fully taken into account. The coupling between impeller and volute is implemented by means of the frozen rotor method. The simulation results predicted indicate that the solid phase properties in two-phase flow, especially the concentration, the particle diameter and the density, have strong effects on the hydraulic performance of the pump. Both the pump head and the efficiency are reduced with increasing particle diameter or concentration. However, the effect of particle density on the performance is relatively minor. An obvious jet-wake flow structure is presented near the volute tongue and becomes more remarkable with increasing solid phase concentration. The suction side of the blade is subject to much more severe abrasion than the pressure side. The obtained results preliminarily reveal the characteristics of solid-liquid two-phase flow in the centrifugal pump, and are helpful for improvement and empirical correction in the hydraulic design of centrifugal pumps.

关键词： centrifugal pump solid-liquid two-phase particle property hydraulic performance abrasion numerical simulation

倾斜布管采控天然冷量的青藏铁路路基温度场演变规律(英文)

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倾斜布管采控天然冷量的青藏铁路路基温度场演变规律(英文)