Monitoring Of Permafrost Deformation Along Moscow-kazan High-speed Railway Based On Time Series InSAR Method

Permafrost is a kind of soil which is sensitive to temperature,and the underground ice resources are abundant.The state of underground ice changes with the change of temperature.As the temperature rises in spring and summer,the ice melts into water.In autumn and winter,the temperature drops and the water freezes into ice.Therefore,the project construction in the tundra area is faced with two major risks: frost heave and thawing.As the climate warms,permafrost is deteriorating.In order to reduce the damage caused by ground subsidence to engineering structures and people’s life,it is necessary to monitor the ground subsidence in oil frozen soil area.At present,SAR interferometry technology has the advantages of all-weather,all-weather,high resolution,high precision,high efficiency and wide monitoring range,etc.It has been widely used in surface subsidence monitoring work,and it has incomparable advantages in surface subsidence monitoring work in a large range.With the promotion of "One Belt And One Road" strategy,China’s high-speed railway is developing overseas.In 2015,the Moscow-Kazan-Yekaterinburg high-speed railway project began.This project is conducive to the construction of a high-speed transport corridor between Europe and Asia,and is of great significance for accelerating the construction of the "silk road economic belt".The 7,70 km of high-speed rail line is dotted with seasonal permafrost.Repeated alternating activities of thawing and freezing of permafrost along the line will cause uneven deformation of railway roadbed and seriously affect railway operation.Therefore,it is of great significance to obtain the permafrost distribution information in the tundra region based on certain monitoring methods,and carry out surface deformation inversion of seasonal permafrost along the line,so as to reveal the deformation law and development trend of the permafrost.In this paper,the Moscow-Vladimir section of Moscow-Kazan high-speed railway is taken as the research area,and the surface temperature is retrieved by thermal infrared remote sensing.The surface subsidence in the study area was monitored by DIn SAR and di time series In SAR respectively,and the surface deformation characteristics along the railway were studied.The relationship between the distribution of permafrost,the development of permafrost and the surface deformation is discussed.The specific work contents and results of this paper are as follows:1.Surface temperature inversion of Lansat8 image data in the research area was performed based on atmospheric correction method.The threshold method is used to calculate the places where there are clouds in the temperature data.Then the surface temperature data were obtained by calculating the surface radiation ratio,combining with the atmospheric parameters provided by NASA at the transit time to calculate the surface radiation intensity and the inverse function of Planck’s formula.2.By calculating the average surface temperature and the image sequence of the low-temperature region,the criteria for determining the frozen soil were formulated,and the division of the frozen soil in the moscow-vladimir section was completed.Among the five stations along the moscow-vladimir high-speed railway,the permafrost distribution between kursk station and nokinsk station in the first half of the railway is relatively scattered,and in the second half there is a large area of seasonal permafrost between olekhovo-zuyev station and vladimir station.3.For the Moscow-Vladimir region where there is a large amount of seasonal permafrost.DIn SAR was used to construct spring-summer and autumn-winter interference pairs,and it was found that there was a certain seasonal deformation on the surface of the study area.The distribution of surface deformation in the study area is located in the region of frozen soil obtained by inversion,which indicates that the surface deformation in this area is mainly caused by seasonal variation of frozen soil.4.The surface deformation in the study area was further monitored with the di time series In SAR technology,and two subsidence areas in the study area were analyzed according to the deformation results of the time series and temperature data.The maximum surface subsidence rate of frozen soil in chernogorovka region is-76.3mm/year.The freezing period begins in late October,and the melting period begins in mid-february.The maximum surface subsidence rate of frozen soil in danilovka region is-58.4mm/year.The freezing period begins in mid-december and the thawing period begins in late February.At the same time,it is found that the freezing and thawing of permafrost is closely related to the surface water resources,and the permafrost surface is more prone to change in regions with abundant water resources.