The sideward permafrost along the Qinghai-Tibet Highway (QTH) contains massive ground-ice and is at a relatively high temperature.Under the influence of the steady increase of human activities,the permafrost environme...The sideward permafrost along the Qinghai-Tibet Highway (QTH) contains massive ground-ice and is at a relatively high temperature.Under the influence of the steady increase of human activities,the permafrost environment has been changed greatly for a long time.At present,the permafrost becomes warm and rapidly degenerates,including the decline of the permafrost table,rising of the ground temperature,shortening of the length of frozen section,and extension of range of melting region.Some thaw hazards (e.g.thaw slumping and thermokarst pond) have widely occurred along both sides of the roadbed.In addition,due to the incomplete construction management,the vegetation adjacent to the highway is seriously damaged or eradicated,resulting in the land desertification and ecosystem out of balance.The dust,waste and garbage brought by drivers,passengers,maintenance workers,and transportations may also pollute the permafrost environment.展开更多
Embankment stability is the primary problem for the expressway construction in permafrost regions.The proposed Qinghai-Tibet Expressway(QTE)is planned to construct along the Qinghai-Tibet Project Corridor.Confronted w...Embankment stability is the primary problem for the expressway construction in permafrost regions.The proposed Qinghai-Tibet Expressway(QTE)is planned to construct along the Qinghai-Tibet Project Corridor.Confronted with harsh environmental condition and intense heat exchange between earth and atmosphere,it is necessary to predict and evaluate the stability of the proposed QTE.In this study,the factors affecting the embankment stability are analyzed firstly.And then,a scheme for the stability evaluation of the embankment is established.Finally,the evaluation scheme is used for the pre-evaluation of the stability for the proposed QTE with different geothermal regulation measures(GRMs).The results indicate that the influencing factors include climatic environment,permafrost property,engineering condition and geological condition,and among them,engineering condition and permafrost property are the main influence factors for embankment stability.The stability of the proposed QTE varies greatly in the different geomorphological regions.The application effect and contribution to embankment stability of the existing GRMs are different,and using GRMs cannot completely overcome the influence of various factors on expressway stability.In the construction process,different GRMs should be adopted depending on the geomorphological environment where the embankment is located to ensure the embankment stability.展开更多
This study investigated the temperature field and thawing depth of wide embankment for expressway in permafrost regions based on numerical analysis by using finite element method(FEM).According to specific embankment ...This study investigated the temperature field and thawing depth of wide embankment for expressway in permafrost regions based on numerical analysis by using finite element method(FEM).According to specific embankment section of Qinghai-Tibet highway,computational region for numerical analysis was defined.And numerical model was developed through FEM software named as ABAQUS and was verified by field observed data.The effects by width and height of embankment on the thermal regime of computational region were analyzed based on FEM modeling.Numerical analysis showed that embankment construction has serious disturbance on the thermal stability of ground permafrost showing as annual average ground temperature and the maximum thawing depth keeps increasing with service time increasing.And larger embankment width leads to poorer thermal stability and more serious uneven temperature field of embankment.Raising embankment height can improve the thermal stability; however,the improvement is restricted for wide embankment and it cannot change the degradation trend of thermal stability with service life increasing.Thus,to construct expressway with wide embankment in permafrost regions of Qinghai-Tibet Plateau,effective measures need to be considered to improve the thermal stability of underlying permafrost.展开更多
Based on long-term monitoring data, the relationships between permafrost degradation and embankment deformation are analyzed along the Qinghai-Tibet Highway(QTH). Due to heat absorbing effect of asphalt pavement and c...Based on long-term monitoring data, the relationships between permafrost degradation and embankment deformation are analyzed along the Qinghai-Tibet Highway(QTH). Due to heat absorbing effect of asphalt pavement and climate warming,permafrost beneath asphalt pavement experienced significant warming and degradation. During the monitoring period, warming amplitude of the soil at depth of 5 m under asphalt ranged from 0.21 °C at the XD1 site to 0.5 °C at the KL1 site. And at depth of 10 m, the increase amplitude of ground temperature ranged from 0.47 °C at the NA1 site to 0.07 °C at the XD1 site. Along with ground temperature increase, permafrost table beneath asphalt pavement decline considerably. Amplitude of permafrost table decline varied from 0.53 m at the KL1 site to 3.51 m at the NA1 site, with mean amplitude of 1.65 m for 8 monitoring sites during the monitoring period. Due to permafrost warming and degradation, the embankment deformation all performed as settlement at these sites. At present, those settlements still develop quickly and are expected to continue to increase in the future. The embankment deformations can be divided into homogeneous deformation and inhomogeneous deformation. Embankment longitudinal inhomogeneous deformation causes the wave deformations and has adverse effects on driving comfort and safety, while lateral inhomogeneous deformation causes longitudinal cracks and has an adverse effect on stability. Corresponding with permafrost degradation processes,embankment settlement can be divided into four stages. For QTH, embankment settlement is mainly comprised of thawing consolidation of ice-rich permafrost and creep of warming permafrost beneath permafrost table.展开更多
The permafrost development in the Qinghai-Tibet Engineering Corridor(QTEC)is affected by natural environment changes and human engineering activities.Human engineering activities may damage the permafrost growing envi...The permafrost development in the Qinghai-Tibet Engineering Corridor(QTEC)is affected by natural environment changes and human engineering activities.Human engineering activities may damage the permafrost growing environment,which in turn impact these engineering activities.Thus high spatial-temporal resolution monitoring over the QTEC in the permafrost region is very necessary.This paper presents a method for monitoring the frozen soil area using the intermittent coherencebased small baseline subset(ICSBAS).The method can improve the point density of the results and enhance the interpretability of deformation results by identifying the discontinuous coherent points according to the coherent value of time series.Using the periodic function that models the seasonal variation of permafrost,we separate the long wavelength atmospheric delay and establish an estimation model for the frozen soil deformation.Doing this can raise the monitoring accuracy and improve the understanding of the surface deformation of the frozen soil.In this study,we process 21 PALSAR data acquired by the Alos satellite with the proposed ICSBAS technique.The results show that the frozen soil far from the QTR in the study area experiences frost heave and thaw settlement(4.7 cm to8.4 cm)alternatively,while the maximum settlement along the QTR reaches 12 cm.The interferomatric syntnetic aperture radar(InSAR)-derived results are validated using the ground leveling data nearby the Beiluhe basin.The validation results show the InSAR results have good consistency with the leveling data in displacement rates as well as time series.We also find that the deformation in the permafrost area is correlated with temperature,human activities and topography.Based on the interfering degree of human engineering activities on the permafrost environment,we divide the QTEC along the Qinghai-Tibet Railway into engineering damage zone,transition zone and natural permafrost.展开更多
Aimed at the characteristics of permafrost temperature influencing the safety of Qinghai-Tibet Railway and its on-line testing system, comparing the achievement of permafrost study nationwide with those worldwide, an ...Aimed at the characteristics of permafrost temperature influencing the safety of Qinghai-Tibet Railway and its on-line testing system, comparing the achievement of permafrost study nationwide with those worldwide, an automatic testing system of permafrost temperature, containing a master computer and some slave computers, was designed. By choosing high-precise thermistors as temperature sensor, designing and positioning the depth and interval of testing sections, testing, keeping and sending permafrost temperature data at time over slave computers, and receiving, processing and analyzing the data of collecting permafrost temperature over master computer, the change of the permafrost temperature can be described and analyzed, which can provide information for permafrost railway engineering design. Moreover, by taking permafrost temperature testing in a certain section of Qinghai-Tibet Railway as an instance, the collected data of permafrost temperature were analyzed, and the effect of permafrost behavior was depicted under the railway, as well as, a BP model was set up to predict the permafrost characteristics. This testing system will provide information timely about the change of the permafrost to support the safety operation in Qinghai-Tibet Railway.展开更多
Present-day climate change causing permafrost degradation is most expressed in a zone of discontinuous permafrost with relatively warm temperatures (-1-2℃).Still we observe rather gradual permafrost degradation becau...Present-day climate change causing permafrost degradation is most expressed in a zone of discontinuous permafrost with relatively warm temperatures (-1-2℃).Still we observe rather gradual permafrost degradation because of specific structure of upper permafrost layer.Shur(2005)developed the concept of the transient layer,i.e.a layer of ground between soil active layer and permafrost that cycles展开更多
以东北地区为研究对象,分析多年冻土退化程度及空间分布。通过收集关键气象要素,使用多元线性回归模型修正部分地面温度,基于多年冻土顶部温度(temperature at the top of permafrost,TTOP)模型,利用ANUSPILN软件进行插值,分析东北多年...以东北地区为研究对象,分析多年冻土退化程度及空间分布。通过收集关键气象要素,使用多元线性回归模型修正部分地面温度,基于多年冻土顶部温度(temperature at the top of permafrost,TTOP)模型,利用ANUSPILN软件进行插值,分析东北多年冻土时空分布变化。结果表明,1970 s、1980 s、1990 s、2000 s、2010 s的多年冻土面积分别约为3.99×10^(5)、3.41×10^(5)、2.31×10^(5)、1.80×10^(5)、1.59×10^(5) km^(2)。1970 s—2010 s,东北地区的多年冻土面积显著减少约2.40×10^(5) km^(2),降幅高达60.08%。多年冻土面积占东北地区总面积的比例从27.66%下降至11.04%,而季节性冻土面积比例则从72.34%增加至88.96%。模型结果与实际钻孔数据差值仅为0.05℃,且使用修正地面温度数据的模型结果高于现有研究结果。展开更多
基金Project(KZCX2-YW-Q03-04) supported by the Important Orientation Projects of the Chinese Academy of SciencesProject(41030741) supported by the National Natural Science of ChinaProject(2010CB434813) supported by the National Basic Research Program of China
文摘The sideward permafrost along the Qinghai-Tibet Highway (QTH) contains massive ground-ice and is at a relatively high temperature.Under the influence of the steady increase of human activities,the permafrost environment has been changed greatly for a long time.At present,the permafrost becomes warm and rapidly degenerates,including the decline of the permafrost table,rising of the ground temperature,shortening of the length of frozen section,and extension of range of melting region.Some thaw hazards (e.g.thaw slumping and thermokarst pond) have widely occurred along both sides of the roadbed.In addition,due to the incomplete construction management,the vegetation adjacent to the highway is seriously damaged or eradicated,resulting in the land desertification and ecosystem out of balance.The dust,waste and garbage brought by drivers,passengers,maintenance workers,and transportations may also pollute the permafrost environment.
基金Project(2019QZKK0905)supported by the Second Tibetan Plateau Scientific Expedition and Research(STEP)Program,ChinaProject(41901074)supported by the National Natural Science Foundation of China+2 种基金Project(2020A1515010745)supported by the Natural Science Foundation of Guangdong Province,ChinaProject(SKLFSE201810)supported by the Open Fund of the State Key Laboratory of Frozen Soil Engineering,ChinaProject(2019MS119)supported by the Fundamental Research Funds for the Central Universities,China。
文摘Embankment stability is the primary problem for the expressway construction in permafrost regions.The proposed Qinghai-Tibet Expressway(QTE)is planned to construct along the Qinghai-Tibet Project Corridor.Confronted with harsh environmental condition and intense heat exchange between earth and atmosphere,it is necessary to predict and evaluate the stability of the proposed QTE.In this study,the factors affecting the embankment stability are analyzed firstly.And then,a scheme for the stability evaluation of the embankment is established.Finally,the evaluation scheme is used for the pre-evaluation of the stability for the proposed QTE with different geothermal regulation measures(GRMs).The results indicate that the influencing factors include climatic environment,permafrost property,engineering condition and geological condition,and among them,engineering condition and permafrost property are the main influence factors for embankment stability.The stability of the proposed QTE varies greatly in the different geomorphological regions.The application effect and contribution to embankment stability of the existing GRMs are different,and using GRMs cannot completely overcome the influence of various factors on expressway stability.In the construction process,different GRMs should be adopted depending on the geomorphological environment where the embankment is located to ensure the embankment stability.
基金Project(2014BAG05B04)supported by the National Science and Technology Support Program,ChinaProject(51378006)supported by the National Natural Science Foundation of ChinaProject(2242015R30027)supported by the Excellent Young Teacher Program of Southeast University,China
文摘This study investigated the temperature field and thawing depth of wide embankment for expressway in permafrost regions based on numerical analysis by using finite element method(FEM).According to specific embankment section of Qinghai-Tibet highway,computational region for numerical analysis was defined.And numerical model was developed through FEM software named as ABAQUS and was verified by field observed data.The effects by width and height of embankment on the thermal regime of computational region were analyzed based on FEM modeling.Numerical analysis showed that embankment construction has serious disturbance on the thermal stability of ground permafrost showing as annual average ground temperature and the maximum thawing depth keeps increasing with service time increasing.And larger embankment width leads to poorer thermal stability and more serious uneven temperature field of embankment.Raising embankment height can improve the thermal stability; however,the improvement is restricted for wide embankment and it cannot change the degradation trend of thermal stability with service life increasing.Thus,to construct expressway with wide embankment in permafrost regions of Qinghai-Tibet Plateau,effective measures need to be considered to improve the thermal stability of underlying permafrost.
基金Project(2012CB026106) supported by National Basic Research Program of ChinaProject(2014BAG05B01) supported by National Key Technology Support Program China+1 种基金Project(51Y351211) supported by West Light Program for Talent Cultivation of Chinese Academy of SciencesProject(2013318490010) supported by Ministry of Transport Science and Technology Major Project,China
文摘Based on long-term monitoring data, the relationships between permafrost degradation and embankment deformation are analyzed along the Qinghai-Tibet Highway(QTH). Due to heat absorbing effect of asphalt pavement and climate warming,permafrost beneath asphalt pavement experienced significant warming and degradation. During the monitoring period, warming amplitude of the soil at depth of 5 m under asphalt ranged from 0.21 °C at the XD1 site to 0.5 °C at the KL1 site. And at depth of 10 m, the increase amplitude of ground temperature ranged from 0.47 °C at the NA1 site to 0.07 °C at the XD1 site. Along with ground temperature increase, permafrost table beneath asphalt pavement decline considerably. Amplitude of permafrost table decline varied from 0.53 m at the KL1 site to 3.51 m at the NA1 site, with mean amplitude of 1.65 m for 8 monitoring sites during the monitoring period. Due to permafrost warming and degradation, the embankment deformation all performed as settlement at these sites. At present, those settlements still develop quickly and are expected to continue to increase in the future. The embankment deformations can be divided into homogeneous deformation and inhomogeneous deformation. Embankment longitudinal inhomogeneous deformation causes the wave deformations and has adverse effects on driving comfort and safety, while lateral inhomogeneous deformation causes longitudinal cracks and has an adverse effect on stability. Corresponding with permafrost degradation processes,embankment settlement can be divided into four stages. For QTH, embankment settlement is mainly comprised of thawing consolidation of ice-rich permafrost and creep of warming permafrost beneath permafrost table.
基金supported by the National Natural Science Foundation of China(42174026)the National Key Research and Development Program of China(2021YFE011004)。
文摘The permafrost development in the Qinghai-Tibet Engineering Corridor(QTEC)is affected by natural environment changes and human engineering activities.Human engineering activities may damage the permafrost growing environment,which in turn impact these engineering activities.Thus high spatial-temporal resolution monitoring over the QTEC in the permafrost region is very necessary.This paper presents a method for monitoring the frozen soil area using the intermittent coherencebased small baseline subset(ICSBAS).The method can improve the point density of the results and enhance the interpretability of deformation results by identifying the discontinuous coherent points according to the coherent value of time series.Using the periodic function that models the seasonal variation of permafrost,we separate the long wavelength atmospheric delay and establish an estimation model for the frozen soil deformation.Doing this can raise the monitoring accuracy and improve the understanding of the surface deformation of the frozen soil.In this study,we process 21 PALSAR data acquired by the Alos satellite with the proposed ICSBAS technique.The results show that the frozen soil far from the QTR in the study area experiences frost heave and thaw settlement(4.7 cm to8.4 cm)alternatively,while the maximum settlement along the QTR reaches 12 cm.The interferomatric syntnetic aperture radar(InSAR)-derived results are validated using the ground leveling data nearby the Beiluhe basin.The validation results show the InSAR results have good consistency with the leveling data in displacement rates as well as time series.We also find that the deformation in the permafrost area is correlated with temperature,human activities and topography.Based on the interfering degree of human engineering activities on the permafrost environment,we divide the QTEC along the Qinghai-Tibet Railway into engineering damage zone,transition zone and natural permafrost.
基金Project(2007XM036) supported by the Science and Technology of Beijing Jiaotong University, China
文摘Aimed at the characteristics of permafrost temperature influencing the safety of Qinghai-Tibet Railway and its on-line testing system, comparing the achievement of permafrost study nationwide with those worldwide, an automatic testing system of permafrost temperature, containing a master computer and some slave computers, was designed. By choosing high-precise thermistors as temperature sensor, designing and positioning the depth and interval of testing sections, testing, keeping and sending permafrost temperature data at time over slave computers, and receiving, processing and analyzing the data of collecting permafrost temperature over master computer, the change of the permafrost temperature can be described and analyzed, which can provide information for permafrost railway engineering design. Moreover, by taking permafrost temperature testing in a certain section of Qinghai-Tibet Railway as an instance, the collected data of permafrost temperature were analyzed, and the effect of permafrost behavior was depicted under the railway, as well as, a BP model was set up to predict the permafrost characteristics. This testing system will provide information timely about the change of the permafrost to support the safety operation in Qinghai-Tibet Railway.
文摘Present-day climate change causing permafrost degradation is most expressed in a zone of discontinuous permafrost with relatively warm temperatures (-1-2℃).Still we observe rather gradual permafrost degradation because of specific structure of upper permafrost layer.Shur(2005)developed the concept of the transient layer,i.e.a layer of ground between soil active layer and permafrost that cycles
文摘以东北地区为研究对象,分析多年冻土退化程度及空间分布。通过收集关键气象要素,使用多元线性回归模型修正部分地面温度,基于多年冻土顶部温度(temperature at the top of permafrost,TTOP)模型,利用ANUSPILN软件进行插值,分析东北多年冻土时空分布变化。结果表明,1970 s、1980 s、1990 s、2000 s、2010 s的多年冻土面积分别约为3.99×10^(5)、3.41×10^(5)、2.31×10^(5)、1.80×10^(5)、1.59×10^(5) km^(2)。1970 s—2010 s,东北地区的多年冻土面积显著减少约2.40×10^(5) km^(2),降幅高达60.08%。多年冻土面积占东北地区总面积的比例从27.66%下降至11.04%,而季节性冻土面积比例则从72.34%增加至88.96%。模型结果与实际钻孔数据差值仅为0.05℃,且使用修正地面温度数据的模型结果高于现有研究结果。
