Considering the comprehensive morphology and genesis of Podzols of the Stolowe Mountains,and the still-possible impact of frost actions and other processes related to cold climate on these soils,the main aims of this ...Considering the comprehensive morphology and genesis of Podzols of the Stolowe Mountains,and the still-possible impact of frost actions and other processes related to cold climate on these soils,the main aims of this study were to determine whether(i)the heterogeneous Podzols in the Stolowe Mountains underwent a phase of development in a cold climate,resulting in frost action features visible on the micromorphological level,and whether(ii)contemporary cryopedogenic traces are masked by the translocation of organic matter due to the podzolisation process.Four soil profiles were investigated,revealing distinct layers corresponding to different periods of soil formation.Under field observation,no explicit frost-related characteristics were observed.Nevertheless,micromorphological analysis revealed cappings of fine materials on grains or peds,as well as development of granostriated(or any striated)b-fabric that resulted from the alternating effects of thawing and freezing processes.Moreover,micromorphological analysis revealed the presence of microstructures that could be the result of cryogenic processes,such as platy,angular blocky and lenticular features,as well as plane,vugh and star-shaped void types.The translocation of organic matter during podzolisation modified or concealed the frost-related features that developed during the late Pleistocene and early Holocene.This is evident,for instance,in the accumulation of organic matter on cappings and within soil voids,which further hinders the identification of frost-related characteristics and the interpretation of the soil's evolution.Macromorphological observations enhanced with micromorphological analyses revealed three distinct layers:(i)a young upper layer composed of loose,sandy material;(ii)a deeper layer containing a spodic horizon with frost actions,involving pedofeatures associated with the Pleistocene cold climate and(iii)a deeper subsoil basal layer.The abovementioned microstructures,combined with lithological discontinuity,support the hypothesised polygenetic origin of Podzols in the studied region.展开更多
Uneven frost heave deformation can shorten the operational lifespan of foundation engineering.Clarifying the mechanisms of uneven frost heave facilitates the targeted mitigation of frost damage.This study focused on a...Uneven frost heave deformation can shorten the operational lifespan of foundation engineering.Clarifying the mechanisms of uneven frost heave facilitates the targeted mitigation of frost damage.This study focused on a water conveyance channel in Jilin Province,northern China,and found after monitoring that the frost heave at the channel bottom lining exceeded that at the crest by 44.5 mm,with the freezing temperature at the bottom being over 2℃lower than that at the crest.Soil columns with an initial gravimetric moisture content of 12%,16%,18%,and 20%were then prepared.The effects of temperature and moisture content on frost heave were analyzed under two freezing conditions(-5℃and-10℃)through unidirectional freezing tests.A coupled thermo-hydro-mechanical(THM)frost heave model,validated by the test results,was further established.In the soil with an initial moisture content of 20%,the formation of ice lenses associated with substantial water migration contributed to a large temperature gradient,which can jointly induce frost heave.Under the-10℃condition,the temperature gradient in the soil column with a 20%initial moisture content reached 0.84℃/cm,the total water migration reached 10.72%,and the frost heave deformation was 1.86 mm.The THM coupling results indicated that,under the interaction of a large temperature gradient and moisture accumulation,the volumetric ice content remained high in the bottom soil during freezing and peaked at 0.36.The frost damage to the bottom soil was severe,and the maximum deformation reached 57 mm.展开更多
One reference in the original manuscript contained incorrect bibliographic information and cited a non-existent publication:Traczyk A(1999)Pleistocene debris cover beds and block-debris tongues in the north-western pa...One reference in the original manuscript contained incorrect bibliographic information and cited a non-existent publication:Traczyk A(1999)Pleistocene debris cover beds and block-debris tongues in the north-western part of theŚlęża Massif(Poland)and their formation under permafrost conditions.Geographia Polonica 81(1).This erroneous reference has now been removed from the references list.展开更多
Frost heave in water-bearing rock masses poses significant threats to geotechnical engineering.This paper developed a novel three-dimensional(3D)frost model,based on the combined finite-discrete element method(FDEM),t...Frost heave in water-bearing rock masses poses significant threats to geotechnical engineering.This paper developed a novel three-dimensional(3D)frost model,based on the combined finite-discrete element method(FDEM),to investigate the frost heave process in rock masses where thermal transfer,water migration,water-ice phase transition(ice growth)and ice-rock interaction are explicitly simulated.The proposed model is first validated against existing experimental and analytical solutions,and further applied to investigate path-dependent frost heave behavior under various freezing conditions.Results show that freezing direction plays a vital role in the dynamic ice growth and ice-rock interaction,thus affecting the frost heave behavior.In the top-down freezing regime,ice plugs form first at the crack's top surface,sealing the crack and preventing water migration,which can amplify ice pressure.Parametric studies,including rock Young's modulus,ice-rock friction,and rock hydraulic conductivity,further reveal that the temporal aspects of ice development and rock mechanical response strongly affect ice-rock interaction and hence the frost heave mechanism.Furthermore,some typical phenomena(e.g.water/ice extrusion and frost cracking)can also be well captured in this model.This novel numerical framework sheds new light on frost heave behavior and enriches our understanding of frost heave mechanisms and ice-rock interaction processes within cold environment engineering projects.展开更多
Frost heave in seasonally frozen regions is a one-dimensional process that could severely damage infrastructure subgrades.Stress state,temperature and water migration are important factors for frost heave.This work in...Frost heave in seasonally frozen regions is a one-dimensional process that could severely damage infrastructure subgrades.Stress state,temperature and water migration are important factors for frost heave.This work investigated the effects of soil temperature and volumetric water content on the transient frost heave ratio during the freezing of saturated silty clay in an open system and analyzed the relationships between the transient frost heave ratio and freezing rate and between temperature gradient and frost heave rate.The results show that the frost heave ratio,frost heave rate,and freezing rate are positively correlated with the temperature gradient since the temperature gradient drives the water migration during freezing,indicating the transient temperature gradient could be used to evaluate the frost heave of saturated silty clay.The transient freezing rate and transient frost heave ratio are logarithmically related to the transient frost heave ratio and transient temperature gradient,respectively.The effects of transient temperature gradient on frost heave are the principal mechanism responsible for different frost heave characteristics and uneven frost heave along a subgrade of the same soil type.展开更多
Climate change differentially influences the frozen ground,a major dynamic component of the cryosphere,on a local and regional scale.Under the warming climate with pronounced effects reported at higher altitudes,the c...Climate change differentially influences the frozen ground,a major dynamic component of the cryosphere,on a local and regional scale.Under the warming climate with pronounced effects reported at higher altitudes,the characterization of the frozen ground is very important in the Upper Indus Basin(UIB),an important and critical region with respect to climate and hydro-glaciological dynamics.In this study,the efficiency and reliability of the surface frost number model are assessed in delineating the spatial extent of different classes of frozen ground in the region.The daily MODIS land surface temperature(LST)with ground surface temperature(GST)and surface geomorphological expressions as ground validation datasets are used jointly in efficiently determining the extent of different classes of frozen ground(continuous and discontinuous permafrost and seasonal frost).The LST and GST resonate with each other in the annual cycle of temperature variation,however,with mean annual LST exhibiting an offset(cold bias)of 5 to 7℃relative to mean GST.This study shows that the highest permafrost extent is observed in areas where the lowest thinning rates of glacier ice are reported and vice versa.The surface frost number model categorizes an area of 38%±3%and 15%±3%in the UIB as permafrost and seasonal frost,respectively.Based on the altitude model,the lower limit of alpine permafrost is approximated at a mean altitude of 4919±590 m a.s.l.in the UIB.The present study acts as preliminary work in the data sparse and inaccessible regions of the UIB in characterizing the frozen and unfrozen ground and may act as a promising input data source in glaciohydro-meteorological models for the Himalaya and Karakoram.In addition,the study also underlines the consideration of this derelict cryospheric climatic variable in defining and accounting for the sustainable development of socio-economic systems through its intricate ramification on agricultural activity,landscape stability and infrastructure.展开更多
The frost growth on cold surfaces in evaporators is an undesirable phenomenon which becomes a problem for the thermal efficiency of the refrigeration systems because the ice layer acts as a thermal insulation,drastica...The frost growth on cold surfaces in evaporators is an undesirable phenomenon which becomes a problem for the thermal efficiency of the refrigeration systems because the ice layer acts as a thermal insulation,drastically reducing the rate of heat transfer in the system.Its accumulation implies an increase in energy demand and a decrease in the performance of various components involved in the refrigeration process,reducing its efficiency and making it necessary to periodically remove the frost,resulting in expenses for the defrost process.In the present work,a numerical-experimental analysis was performed in order to understand the formation process of porous ice in flat plates with different surface treatments and parameters.This understanding is of utmost importance to minimize the formation of porous ice on cold surfaces and improve equipment efficiency and performance.In this context,a low-cost experimental apparatus was developed,enabling an experimental analysis of the phenomenon under study.The environmental conditions evaluated are the temperature of the cold surface,roomtemperature,humidity,and air velocity.The material of the surfaces under study are aluminum,copper,and brass with different surface finishes,designated as smooth,grooved(hydrophilic),and varnished(hydrophobic).The numerical-experimental analysis demonstrates measurements and simulations of the thickness,surface temperature,and growth rate of the porous ice layer as a function of the elapsed time.The numerical results were in good agreement with the experimental results,indicating that the varnished surface,with hydrophobic characteristics,presents greater difficulty in providing the phenomenon.Therefore,the results showed that application of a coating allowed a significant reduction on the frost formation process contributing to the improvement of thermal efficiency and performance of refrigeration systems.展开更多
[Objective]The aim was to understand the change characteristics of sugarcane traits and evaluate the cold tolerance of sugarcane varieties under the drought and frost conditions.[Method] The experiment was carried out...[Objective]The aim was to understand the change characteristics of sugarcane traits and evaluate the cold tolerance of sugarcane varieties under the drought and frost conditions.[Method] The experiment was carried out in Ziyuan County,Guangxi Province where the frost occurred often with 21 domestic and abroad sugarcane varieties（elites）.[Result] There were significant changes in the brix,green leaf number and photosynthetic rate of sugarcane before and after light frost and decreased more in cold-sensitive varieties.However,the correlation was only significant between the damage rate of stem length and internode,percentage of green leaves after heavy frost in relation to sugarcane brix and brix changes after light frost.Further analysis showed that the evaluation for cold tolerance of sugarcane would be more simple and reliable with traits of the damage rate of stem length and percentage of upper green leaves.The evaluation for varieties indicated that if it was not carried out for cold-tolerance identification in breeding program,the percentage of sugarcane varieties with good cold-tolerance will be lower than30%,and higher than 60% with poor cold-tolerance in subtropical and tropical regions.[Conclusion] This study had provided theoretical basis for the cold-resistant evaluation of sugar cane and the breeding of the varieties of cold-resistant.展开更多
The temperate monsoon area of China is an important agricultural region but late spring frosts have frequently caused significant damage to plants there. Based on phenological data derived from the Chinese Phenologica...The temperate monsoon area of China is an important agricultural region but late spring frosts have frequently caused significant damage to plants there. Based on phenological data derived from the Chinese Phenological Observation Network （CPON）, corresponding meteorological data from 12 study sites and phenological modeling, changes in flowering times of multiple woody plants and the frequency of frost occurrence were analyzed. Through these analyses, frost risk during the flowering period at each site was estimated. Results of these estimates suggested that first flowering dates （FFD） in the study area advanced significantly from 1963 to 2009 at an average rate of -1.52 days/decade in North-east China （P〈0.01） and -2.22 days/decade （P〈0.01） in North China. Over the same period, the number of frost days in spring decreased and the last frost days advanced across the study area. Considering both flowering phenology and occurrence of frost, the frost risk index, which measures the percentage of species exposed to frost during the flowering period in spring, exhibited a decreasing trend of -0.37% per decade （insignificant） in Northeast China and -1.80% per decade （P〈0.01） in North China, implying that frost risk has reduced over the past half century. These conclusions provide important information to agriculture and forest managers in devising frost protection schemes in the region.展开更多
Automated over-tree sprinkler irrigation systems were developed and tested in two orchards located in two separate locations in southern Iran （a 0.17 ha peach orchard and a 0.24 ha orange orchard） to protect peach b...Automated over-tree sprinkler irrigation systems were developed and tested in two orchards located in two separate locations in southern Iran （a 0.17 ha peach orchard and a 0.24 ha orange orchard） to protect peach blossoms and orange trees leaves and fruits from low temperature damage. The experiment used a system that monitored the trees and air temperatures using two thermistors. The water application rate by the irrigation system was determined by an energy balance as implemented by the software FROSTPRO, In the peach orchard, the system was tested during three frost events during the spring of 2003 and three other events during the spring of 2004. The system successfully kept peach flowers above the critical temperature, i.e., -4.0℃ in spring 2004 （control block -4.12℃, and sprinkled block ＋0.5℃） during all events. Similar results were obtained in the orange orchard during three frost events in the winter of 2004, during which the tree temperatures were at least 2.5℃ above the critical temperature. Results from field tests show that the system can effectively protect the peach blossoms from damage. Determination done after the frost events showed a 12% blossom kill in the sprinkled blocks while in the unsprinkled control block a 41.5% blossom kill. Calculations indicated that when using variable application rates, the amount of water used can be reduced by 54.3%. Spatial distribution of minimum temperatures during the three frosts was also studied in Jahrom, Iran. Results showed a significant temperature control in the experimental block, especially in the central part of the orchard, but the block margins （about 3.6% of the total area） were at the risk of low temperature due to the wind drift effects.展开更多
Ground temperatures from four of the seven extensively studied highway cross-sections near Gulkana/Glennallen,Alaska during 1954;962,were chosen to better understand the impacts of highway construction on warm permafr...Ground temperatures from four of the seven extensively studied highway cross-sections near Gulkana/Glennallen,Alaska during 1954;962,were chosen to better understand the impacts of highway construction on warm permafrost.Both the thawing of permafrost and seasonal frost action impacted on road surface stability for about 6 years until the maximum summer thaw reached about 3 m in depth.Seasonal frost action caused most of the ensuing stability problems.Unusually warm summers and the lengths of time required to re-freeze the active layer were far more important than the average annual air temperatures in determining the temperatures of the underlying shallow permafrost,or the development of taliks.The hypothesized climate warming would slightly and gradually deepen the active layer and the developed under-lying talik,but its effect would be obscured by unusually warm summers,by warmer than usual winters,and by the vari-able lengths of time of the zero curtains.At least one period of climate mini-cooling in the deeper permafrost during the early 20th century was noted.展开更多
Seasonally cold climate and resulting frost action set great demands to railway track substructure in order to maintain Irack geomelry. Chal- lenges culminate on high-speed lines, where the tolerances for roughness ar...Seasonally cold climate and resulting frost action set great demands to railway track substructure in order to maintain Irack geomelry. Chal- lenges culminate on high-speed lines, where the tolerances for roughness are the tightest. Problems may result in highly increased Irack maintenance and need for temporary speed reslrictions. The causes of frost action can be associated with subsoil, subballast or ballast. The major concern in frost protection is to avoid the freezing of frost susceptible subsoil by using sufficient thickness of subballast and relying on non-fi＇ost-susctible subballast material. This paper provides an overview of the main research findings on the role of ballast, subballast and subsoil in frost acedon. In new comlruclion the material specificalions, design procedures and construction methods have been developed to ensure adequate performance of Irack subscatt, but special challenges exist in managing existing Wacks that were not designed for modem requirements. In order to perform cost-effective and sustainable track maintenance, it is necessary to recognize the problem areas and define the root-causes of problems. For locating the problem sections and defining the causes of defects, a sophisticated analysis based on integration of track geometry and ground penetrating radar （GPR） data has been developed and is summarized in this paper,展开更多
The building of railways on seasonally frozen ground is inevitable as China pursues economic development and the improvement of its citizens'living standards.However,railway construction in seasonally frozen soil ...The building of railways on seasonally frozen ground is inevitable as China pursues economic development and the improvement of its citizens'living standards.However,railway construction in seasonally frozen soil areas is often faced with frost heave,leading to uneven subgrades which seriously threaten traffic safety.This article summarizes extant research results on frost heave mechanism,frost heave factors,and anti-frost measures of railway subgrades in seasonally frozen soil areas.展开更多
[Objective]The research aimed to study variation characteristics of large-scale frost in the east region of the Yellow River of Gansu in recent 40 years.[Method]Based on daily minimum temperature data at 15 meteorolog...[Objective]The research aimed to study variation characteristics of large-scale frost in the east region of the Yellow River of Gansu in recent 40 years.[Method]Based on daily minimum temperature data at 15 meteorological stations over the east region of the Yellow River of Gansu from 1969 to 2008,according to common climatic statistical index of the frost,variation characteristics of the large-scale frost and continuous frost in the east region of the Yellow River of Gansu in recent 40 years were studied.[Result]Since the 1990s,average last frost date in the east region of the Yellow River of Gansu obviously advanced,and first frost date started to obviously postpone.Advancing time of the last frost date was longer than postponing time of the first frost date.Average frost-free period also obviously prolonged.Extremely early first frost date and extremely late last frost date mainly happened in the 1970s and the 1980s.Extremely late first frost date and extremely early last frost date mainly happened after the middle period of the 1990s.Extremely long frost-free period gradually started to appear frequently.In recent 40 years,the continuous frost gradually decreased,and the intensity also declined.[Conclusion]The research was favorable for understanding change characteristics of the frost and climate in the east region of the Yellow River of Gansu,and had important guidance significance for improving prediction capability of the abnormal frost disaster,effectively preventing frost disaster and improving crop yield in the area.展开更多
Frost susceptibility is a concept widely used in cold region geotechnical design, to quantify the capacity of a soil in generating frost heave and frost damage. The laboratory test used to verify frost susceptibility ...Frost susceptibility is a concept widely used in cold region geotechnical design, to quantify the capacity of a soil in generating frost heave and frost damage. The laboratory test used to verify frost susceptibility of a soil is based on the measurement of frost heave generated in the soil under specific conditions. In reality this concept is, however, more related to the soil's potential to thaw weakening than to frost heave. Recent experimental studies show that frost non-susceptible soils like clean sand and clean gavel can also generate much ice segregation and frost heave if the conditions are favourable, hence challenging the usefulness and suitability of soil classification based on frost susceptibility. It is further shown that the concept is not suitable for design scenarios where frost heave itself is a serious hazard, such as in high-speed rail embankments.展开更多
[Objective] The research aimed to study the climate variation characteristics of frost in Shandong Province. [Method] The daily minimum surface temperature ≤ 0 ℃ in autumn or spring was as the frost index. Based on ...[Objective] The research aimed to study the climate variation characteristics of frost in Shandong Province. [Method] The daily minimum surface temperature ≤ 0 ℃ in autumn or spring was as the frost index. Based on the daily minimum surface temperature data in 67 meteorological observatories of Shandong Province during 1961-2008, the variation characteristics of first, last frost dates and frost-free period in Shandong Province were analyzed by using the climate diagnosis analysis method. [Result] The climate characteristics of first, last frost dates and frost-free period had the obvious geographical differences in Shandong Province in recent 48 years. The extreme differences of first, last frost dates and frost-free period were all above the three times of their standard deviations. It illustrated that the dispersion degrees of first, last dates and frost-free period were all very big. The average first frost date postponed with 1.99 d/10 a velocity in Shandong Province in recent 48 years, and the last frost date advanced with 1.46 d/10 a velocity. The postponing range of first frost date was bigger than the advancing range of last frost date, and the frost-free period prolonged with 3.42 d/10 a velocity. Seen from the interdecadal variations, the first frost date started to obviously postpone, and the last frost date obviously advanced since the 1990s. The frost-free period also started to obviously prolong since the 1990s. [Conclusion] The research provided the certain reference for the predication, prevention of frost disaster and the structure adjustment of crops.展开更多
Against the background of global warming, environmental and ecological problems caused by frozen ground degradation have become a focus of attention for the scientific community. As the temperature rises, the permafro...Against the background of global warming, environmental and ecological problems caused by frozen ground degradation have become a focus of attention for the scientific community. As the temperature rises, the permafrost is degrading significantly in the frozen ground region of northeast China(FGRN China). At present, research on FGRN China is based mainly on data from meteorological stations, and the research period has been short.In this study, we analyzed spatial and temporal variation in the ground surface freezing index(GFI) and ground surface thawing index(GTI) from 1900 to 2017 for FGRN China, with the air freezing index(AFI) and air thawing index(ATI) using the University of Delaware(UDEL)monthly gridded air temperature dataset. The turning point year for annual mean air temperature(AMAT) was identified as 1985, and the turning point years for GFI and GTI were 1977 and 1996. The air temperature increased by 0.01 ℃ per year during 1900–2017, and the GFI and GTI increased at rates of –0.4 and 0.5 ℃ d per year before the turning point year;after the turning point, these rates were –0.7 and –2.1 ℃ d per year. We utilized a surface frost number model to study the distribution of frozen ground in FGRN China from 1900 to 2017.When the empirical coefficient E value is 0.57, the simulated frozen ground distribution is basically consistent with the existing frozen ground maps. The total area of permafrost in FGRN China decreased by 22.66×10^(4) km^(2) from 1900 to 2017, and the permafrost boundary moved northward with obvious degradation. The results of this study demonstrate the trend in permafrost boundary degradation in FGRN China, and provide basic data for research on the hydrological, climate, and ecological changes caused by permafrost degradation.展开更多
基金financed by the Wroclaw University of Environmental and Life Sciences(Poland)。
文摘Considering the comprehensive morphology and genesis of Podzols of the Stolowe Mountains,and the still-possible impact of frost actions and other processes related to cold climate on these soils,the main aims of this study were to determine whether(i)the heterogeneous Podzols in the Stolowe Mountains underwent a phase of development in a cold climate,resulting in frost action features visible on the micromorphological level,and whether(ii)contemporary cryopedogenic traces are masked by the translocation of organic matter due to the podzolisation process.Four soil profiles were investigated,revealing distinct layers corresponding to different periods of soil formation.Under field observation,no explicit frost-related characteristics were observed.Nevertheless,micromorphological analysis revealed cappings of fine materials on grains or peds,as well as development of granostriated(or any striated)b-fabric that resulted from the alternating effects of thawing and freezing processes.Moreover,micromorphological analysis revealed the presence of microstructures that could be the result of cryogenic processes,such as platy,angular blocky and lenticular features,as well as plane,vugh and star-shaped void types.The translocation of organic matter during podzolisation modified or concealed the frost-related features that developed during the late Pleistocene and early Holocene.This is evident,for instance,in the accumulation of organic matter on cappings and within soil voids,which further hinders the identification of frost-related characteristics and the interpretation of the soil's evolution.Macromorphological observations enhanced with micromorphological analyses revealed three distinct layers:(i)a young upper layer composed of loose,sandy material;(ii)a deeper layer containing a spodic horizon with frost actions,involving pedofeatures associated with the Pleistocene cold climate and(iii)a deeper subsoil basal layer.The abovementioned microstructures,combined with lithological discontinuity,support the hypothesised polygenetic origin of Podzols in the studied region.
基金funding support from the National Natural Science Foundation of China(Grants Nos.42330708 and 42302329)the Graduate Innovation Research Program of Jilin University(Grant No.2024CX118).
文摘Uneven frost heave deformation can shorten the operational lifespan of foundation engineering.Clarifying the mechanisms of uneven frost heave facilitates the targeted mitigation of frost damage.This study focused on a water conveyance channel in Jilin Province,northern China,and found after monitoring that the frost heave at the channel bottom lining exceeded that at the crest by 44.5 mm,with the freezing temperature at the bottom being over 2℃lower than that at the crest.Soil columns with an initial gravimetric moisture content of 12%,16%,18%,and 20%were then prepared.The effects of temperature and moisture content on frost heave were analyzed under two freezing conditions(-5℃and-10℃)through unidirectional freezing tests.A coupled thermo-hydro-mechanical(THM)frost heave model,validated by the test results,was further established.In the soil with an initial moisture content of 20%,the formation of ice lenses associated with substantial water migration contributed to a large temperature gradient,which can jointly induce frost heave.Under the-10℃condition,the temperature gradient in the soil column with a 20%initial moisture content reached 0.84℃/cm,the total water migration reached 10.72%,and the frost heave deformation was 1.86 mm.The THM coupling results indicated that,under the interaction of a large temperature gradient and moisture accumulation,the volumetric ice content remained high in the bottom soil during freezing and peaked at 0.36.The frost damage to the bottom soil was severe,and the maximum deformation reached 57 mm.
文摘One reference in the original manuscript contained incorrect bibliographic information and cited a non-existent publication:Traczyk A(1999)Pleistocene debris cover beds and block-debris tongues in the north-western part of theŚlęża Massif(Poland)and their formation under permafrost conditions.Geographia Polonica 81(1).This erroneous reference has now been removed from the references list.
基金supported by the Natural Sciences and Engineering Research Council of Canada(Grant Nos.Discovery 341275,and CRDPJ 543894-19)NSERC/Energi Simulation Industrial Research Chair programState Key Laboratory of Geohazard Prevention and Geoenvironment Protection Open Fund(Grant No.SKLGP2024K001).
文摘Frost heave in water-bearing rock masses poses significant threats to geotechnical engineering.This paper developed a novel three-dimensional(3D)frost model,based on the combined finite-discrete element method(FDEM),to investigate the frost heave process in rock masses where thermal transfer,water migration,water-ice phase transition(ice growth)and ice-rock interaction are explicitly simulated.The proposed model is first validated against existing experimental and analytical solutions,and further applied to investigate path-dependent frost heave behavior under various freezing conditions.Results show that freezing direction plays a vital role in the dynamic ice growth and ice-rock interaction,thus affecting the frost heave behavior.In the top-down freezing regime,ice plugs form first at the crack's top surface,sealing the crack and preventing water migration,which can amplify ice pressure.Parametric studies,including rock Young's modulus,ice-rock friction,and rock hydraulic conductivity,further reveal that the temporal aspects of ice development and rock mechanical response strongly affect ice-rock interaction and hence the frost heave mechanism.Furthermore,some typical phenomena(e.g.water/ice extrusion and frost cracking)can also be well captured in this model.This novel numerical framework sheds new light on frost heave behavior and enriches our understanding of frost heave mechanisms and ice-rock interaction processes within cold environment engineering projects.
基金supported by the National Natural Science Foundation of China(No.51808128)the Natural Science Foundation of Fujian Province(No.2022J01091)。
文摘Frost heave in seasonally frozen regions is a one-dimensional process that could severely damage infrastructure subgrades.Stress state,temperature and water migration are important factors for frost heave.This work investigated the effects of soil temperature and volumetric water content on the transient frost heave ratio during the freezing of saturated silty clay in an open system and analyzed the relationships between the transient frost heave ratio and freezing rate and between temperature gradient and frost heave rate.The results show that the frost heave ratio,frost heave rate,and freezing rate are positively correlated with the temperature gradient since the temperature gradient drives the water migration during freezing,indicating the transient temperature gradient could be used to evaluate the frost heave of saturated silty clay.The transient freezing rate and transient frost heave ratio are logarithmically related to the transient frost heave ratio and transient temperature gradient,respectively.The effects of transient temperature gradient on frost heave are the principal mechanism responsible for different frost heave characteristics and uneven frost heave along a subgrade of the same soil type.
基金the National Mission on Himalayan Studies(NMHS),Ministry of Environment,Forest and Climate Change(MoEFCC)for the financial support under the research project number(GBPNI/NMHS-2019-20/MG)。
文摘Climate change differentially influences the frozen ground,a major dynamic component of the cryosphere,on a local and regional scale.Under the warming climate with pronounced effects reported at higher altitudes,the characterization of the frozen ground is very important in the Upper Indus Basin(UIB),an important and critical region with respect to climate and hydro-glaciological dynamics.In this study,the efficiency and reliability of the surface frost number model are assessed in delineating the spatial extent of different classes of frozen ground in the region.The daily MODIS land surface temperature(LST)with ground surface temperature(GST)and surface geomorphological expressions as ground validation datasets are used jointly in efficiently determining the extent of different classes of frozen ground(continuous and discontinuous permafrost and seasonal frost).The LST and GST resonate with each other in the annual cycle of temperature variation,however,with mean annual LST exhibiting an offset(cold bias)of 5 to 7℃relative to mean GST.This study shows that the highest permafrost extent is observed in areas where the lowest thinning rates of glacier ice are reported and vice versa.The surface frost number model categorizes an area of 38%±3%and 15%±3%in the UIB as permafrost and seasonal frost,respectively.Based on the altitude model,the lower limit of alpine permafrost is approximated at a mean altitude of 4919±590 m a.s.l.in the UIB.The present study acts as preliminary work in the data sparse and inaccessible regions of the UIB in characterizing the frozen and unfrozen ground and may act as a promising input data source in glaciohydro-meteorological models for the Himalaya and Karakoram.In addition,the study also underlines the consideration of this derelict cryospheric climatic variable in defining and accounting for the sustainable development of socio-economic systems through its intricate ramification on agricultural activity,landscape stability and infrastructure.
文摘The frost growth on cold surfaces in evaporators is an undesirable phenomenon which becomes a problem for the thermal efficiency of the refrigeration systems because the ice layer acts as a thermal insulation,drastically reducing the rate of heat transfer in the system.Its accumulation implies an increase in energy demand and a decrease in the performance of various components involved in the refrigeration process,reducing its efficiency and making it necessary to periodically remove the frost,resulting in expenses for the defrost process.In the present work,a numerical-experimental analysis was performed in order to understand the formation process of porous ice in flat plates with different surface treatments and parameters.This understanding is of utmost importance to minimize the formation of porous ice on cold surfaces and improve equipment efficiency and performance.In this context,a low-cost experimental apparatus was developed,enabling an experimental analysis of the phenomenon under study.The environmental conditions evaluated are the temperature of the cold surface,roomtemperature,humidity,and air velocity.The material of the surfaces under study are aluminum,copper,and brass with different surface finishes,designated as smooth,grooved(hydrophilic),and varnished(hydrophobic).The numerical-experimental analysis demonstrates measurements and simulations of the thickness,surface temperature,and growth rate of the porous ice layer as a function of the elapsed time.The numerical results were in good agreement with the experimental results,indicating that the varnished surface,with hydrophobic characteristics,presents greater difficulty in providing the phenomenon.Therefore,the results showed that application of a coating allowed a significant reduction on the frost formation process contributing to the improvement of thermal efficiency and performance of refrigeration systems.
基金Supported by National Science and Technology Support Program(2008BADB8B01,2007BAD30B02,2007BAD30B05)Modern Agricultural Technology System Special Fund Project(nycytx-024-01-03)Guangxi Scientific and Technological Project(0782004-2,0782004-5)~~
文摘[Objective]The aim was to understand the change characteristics of sugarcane traits and evaluate the cold tolerance of sugarcane varieties under the drought and frost conditions.[Method] The experiment was carried out in Ziyuan County,Guangxi Province where the frost occurred often with 21 domestic and abroad sugarcane varieties（elites）.[Result] There were significant changes in the brix,green leaf number and photosynthetic rate of sugarcane before and after light frost and decreased more in cold-sensitive varieties.However,the correlation was only significant between the damage rate of stem length and internode,percentage of green leaves after heavy frost in relation to sugarcane brix and brix changes after light frost.Further analysis showed that the evaluation for cold tolerance of sugarcane would be more simple and reliable with traits of the damage rate of stem length and percentage of upper green leaves.The evaluation for varieties indicated that if it was not carried out for cold-tolerance identification in breeding program,the percentage of sugarcane varieties with good cold-tolerance will be lower than30%,and higher than 60% with poor cold-tolerance in subtropical and tropical regions.[Conclusion] This study had provided theoretical basis for the cold-resistant evaluation of sugar cane and the breeding of the varieties of cold-resistant.
基金Key Project of National Natural Science Foundation of China,No.41030101 National Basic Research Program of China,No.2012CB955304+1 种基金 National Natural Science Foundation of China,No.41171043 ＂Strategic Priority Research Program-Climate Change：Carbon Budget and Relevant Issues＂of the Chinese Academy of Sciences,No.XDA05090301
文摘The temperate monsoon area of China is an important agricultural region but late spring frosts have frequently caused significant damage to plants there. Based on phenological data derived from the Chinese Phenological Observation Network （CPON）, corresponding meteorological data from 12 study sites and phenological modeling, changes in flowering times of multiple woody plants and the frequency of frost occurrence were analyzed. Through these analyses, frost risk during the flowering period at each site was estimated. Results of these estimates suggested that first flowering dates （FFD） in the study area advanced significantly from 1963 to 2009 at an average rate of -1.52 days/decade in North-east China （P〈0.01） and -2.22 days/decade （P〈0.01） in North China. Over the same period, the number of frost days in spring decreased and the last frost days advanced across the study area. Considering both flowering phenology and occurrence of frost, the frost risk index, which measures the percentage of species exposed to frost during the flowering period in spring, exhibited a decreasing trend of -0.37% per decade （insignificant） in Northeast China and -1.80% per decade （P〈0.01） in North China, implying that frost risk has reduced over the past half century. These conclusions provide important information to agriculture and forest managers in devising frost protection schemes in the region.
文摘Automated over-tree sprinkler irrigation systems were developed and tested in two orchards located in two separate locations in southern Iran （a 0.17 ha peach orchard and a 0.24 ha orange orchard） to protect peach blossoms and orange trees leaves and fruits from low temperature damage. The experiment used a system that monitored the trees and air temperatures using two thermistors. The water application rate by the irrigation system was determined by an energy balance as implemented by the software FROSTPRO, In the peach orchard, the system was tested during three frost events during the spring of 2003 and three other events during the spring of 2004. The system successfully kept peach flowers above the critical temperature, i.e., -4.0℃ in spring 2004 （control block -4.12℃, and sprinkled block ＋0.5℃） during all events. Similar results were obtained in the orange orchard during three frost events in the winter of 2004, during which the tree temperatures were at least 2.5℃ above the critical temperature. Results from field tests show that the system can effectively protect the peach blossoms from damage. Determination done after the frost events showed a 12% blossom kill in the sprinkled blocks while in the unsprinkled control block a 41.5% blossom kill. Calculations indicated that when using variable application rates, the amount of water used can be reduced by 54.3%. Spatial distribution of minimum temperatures during the three frosts was also studied in Jahrom, Iran. Results showed a significant temperature control in the experimental block, especially in the central part of the orchard, but the block margins （about 3.6% of the total area） were at the risk of low temperature due to the wind drift effects.
文摘Ground temperatures from four of the seven extensively studied highway cross-sections near Gulkana/Glennallen,Alaska during 1954;962,were chosen to better understand the impacts of highway construction on warm permafrost.Both the thawing of permafrost and seasonal frost action impacted on road surface stability for about 6 years until the maximum summer thaw reached about 3 m in depth.Seasonal frost action caused most of the ensuing stability problems.Unusually warm summers and the lengths of time required to re-freeze the active layer were far more important than the average annual air temperatures in determining the temperatures of the underlying shallow permafrost,or the development of taliks.The hypothesized climate warming would slightly and gradually deepen the active layer and the developed under-lying talik,but its effect would be obscured by unusually warm summers,by warmer than usual winters,and by the vari-able lengths of time of the zero curtains.At least one period of climate mini-cooling in the deeper permafrost during the early 20th century was noted.
基金Finnish Transport Agency for enabling the research
文摘Seasonally cold climate and resulting frost action set great demands to railway track substructure in order to maintain Irack geomelry. Chal- lenges culminate on high-speed lines, where the tolerances for roughness are the tightest. Problems may result in highly increased Irack maintenance and need for temporary speed reslrictions. The causes of frost action can be associated with subsoil, subballast or ballast. The major concern in frost protection is to avoid the freezing of frost susceptible subsoil by using sufficient thickness of subballast and relying on non-fi＇ost-susctible subballast material. This paper provides an overview of the main research findings on the role of ballast, subballast and subsoil in frost acedon. In new comlruclion the material specificalions, design procedures and construction methods have been developed to ensure adequate performance of Irack subscatt, but special challenges exist in managing existing Wacks that were not designed for modem requirements. In order to perform cost-effective and sustainable track maintenance, it is necessary to recognize the problem areas and define the root-causes of problems. For locating the problem sections and defining the causes of defects, a sophisticated analysis based on integration of track geometry and ground penetrating radar （GPR） data has been developed and is summarized in this paper,
基金the Foundation for Excellent Youth Scholars of"Northwest Institute of Eco-Environment and Resources",CAS(grant number:FEYS2019002)the Research Project of State Key Laboratory of Frozen Soil Engineering(grant number:SKLFSE-ZQ-52)the Open Project of State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures,Shijiazhuang Tiedao University(grant number:KF2020-02)。
文摘The building of railways on seasonally frozen ground is inevitable as China pursues economic development and the improvement of its citizens'living standards.However,railway construction in seasonally frozen soil areas is often faced with frost heave,leading to uneven subgrades which seriously threaten traffic safety.This article summarizes extant research results on frost heave mechanism,frost heave factors,and anti-frost measures of railway subgrades in seasonally frozen soil areas.
基金Supported by National Science and Technology Support Plan(2009BAC53B02)National Natural Science Fund Item (41075103)Special Item of the Public Welfare Industry (Meteorology) Science and Research (GYHY201106034,GYHY201006023)
文摘[Objective]The research aimed to study variation characteristics of large-scale frost in the east region of the Yellow River of Gansu in recent 40 years.[Method]Based on daily minimum temperature data at 15 meteorological stations over the east region of the Yellow River of Gansu from 1969 to 2008,according to common climatic statistical index of the frost,variation characteristics of the large-scale frost and continuous frost in the east region of the Yellow River of Gansu in recent 40 years were studied.[Result]Since the 1990s,average last frost date in the east region of the Yellow River of Gansu obviously advanced,and first frost date started to obviously postpone.Advancing time of the last frost date was longer than postponing time of the first frost date.Average frost-free period also obviously prolonged.Extremely early first frost date and extremely late last frost date mainly happened in the 1970s and the 1980s.Extremely late first frost date and extremely early last frost date mainly happened after the middle period of the 1990s.Extremely long frost-free period gradually started to appear frequently.In recent 40 years,the continuous frost gradually decreased,and the intensity also declined.[Conclusion]The research was favorable for understanding change characteristics of the frost and climate in the east region of the Yellow River of Gansu,and had important guidance significance for improving prediction capability of the abnormal frost disaster,effectively preventing frost disaster and improving crop yield in the area.
文摘Frost susceptibility is a concept widely used in cold region geotechnical design, to quantify the capacity of a soil in generating frost heave and frost damage. The laboratory test used to verify frost susceptibility of a soil is based on the measurement of frost heave generated in the soil under specific conditions. In reality this concept is, however, more related to the soil's potential to thaw weakening than to frost heave. Recent experimental studies show that frost non-susceptible soils like clean sand and clean gavel can also generate much ice segregation and frost heave if the conditions are favourable, hence challenging the usefulness and suitability of soil classification based on frost susceptibility. It is further shown that the concept is not suitable for design scenarios where frost heave itself is a serious hazard, such as in high-speed rail embankments.
文摘[Objective] The research aimed to study the climate variation characteristics of frost in Shandong Province. [Method] The daily minimum surface temperature ≤ 0 ℃ in autumn or spring was as the frost index. Based on the daily minimum surface temperature data in 67 meteorological observatories of Shandong Province during 1961-2008, the variation characteristics of first, last frost dates and frost-free period in Shandong Province were analyzed by using the climate diagnosis analysis method. [Result] The climate characteristics of first, last frost dates and frost-free period had the obvious geographical differences in Shandong Province in recent 48 years. The extreme differences of first, last frost dates and frost-free period were all above the three times of their standard deviations. It illustrated that the dispersion degrees of first, last dates and frost-free period were all very big. The average first frost date postponed with 1.99 d/10 a velocity in Shandong Province in recent 48 years, and the last frost date advanced with 1.46 d/10 a velocity. The postponing range of first frost date was bigger than the advancing range of last frost date, and the frost-free period prolonged with 3.42 d/10 a velocity. Seen from the interdecadal variations, the first frost date started to obviously postpone, and the last frost date obviously advanced since the 1990s. The frost-free period also started to obviously prolong since the 1990s. [Conclusion] The research provided the certain reference for the predication, prevention of frost disaster and the structure adjustment of crops.
基金National Natural Science Foundation of China,No.41901072, No.41971151Joint Key Program of the NSFC and Heilongjiang Province of China,No.U20A2082。
文摘Against the background of global warming, environmental and ecological problems caused by frozen ground degradation have become a focus of attention for the scientific community. As the temperature rises, the permafrost is degrading significantly in the frozen ground region of northeast China(FGRN China). At present, research on FGRN China is based mainly on data from meteorological stations, and the research period has been short.In this study, we analyzed spatial and temporal variation in the ground surface freezing index(GFI) and ground surface thawing index(GTI) from 1900 to 2017 for FGRN China, with the air freezing index(AFI) and air thawing index(ATI) using the University of Delaware(UDEL)monthly gridded air temperature dataset. The turning point year for annual mean air temperature(AMAT) was identified as 1985, and the turning point years for GFI and GTI were 1977 and 1996. The air temperature increased by 0.01 ℃ per year during 1900–2017, and the GFI and GTI increased at rates of –0.4 and 0.5 ℃ d per year before the turning point year;after the turning point, these rates were –0.7 and –2.1 ℃ d per year. We utilized a surface frost number model to study the distribution of frozen ground in FGRN China from 1900 to 2017.When the empirical coefficient E value is 0.57, the simulated frozen ground distribution is basically consistent with the existing frozen ground maps. The total area of permafrost in FGRN China decreased by 22.66×10^(4) km^(2) from 1900 to 2017, and the permafrost boundary moved northward with obvious degradation. The results of this study demonstrate the trend in permafrost boundary degradation in FGRN China, and provide basic data for research on the hydrological, climate, and ecological changes caused by permafrost degradation.
