The Study Of Using SBAS To Monitor The Motion Of Frozen Soil Along Qinghai-Tibet Railway

The uneven deformation of subgrade along Qinghai-Tibet railway caused by the freeze/thaw processes of frozen soil will result to settlement and pavement cracks, then destroy the safety operation of train. Therefore, monitoring the ground deformation of the frozen soil along the railway is very important for safety of people and property.It is impossible to obtain large area deformation as well as the deformation time-series by traditional measurements. we can obtain the time deformation sequence by short baseline subset (SBAS) technology based on D-InSAR processing. Considering the seasonal property of frozen soil deformation, we propose period deformation model to replace the linear deformation model of traditional SBAS, and use improved SBAS method to obtain deformation time-series of study area. The main research work includes:(1) The deformation maps of permafrost area along yangbajain-to-dangxum section of Qinghai-Tibet railway for different seasonal are derived using traditional D-InSAR method with ENVISAT ASAR data.(2) The linear deformation model of traditional SBAS approach is not suitable for acquiring the deformation time-series of permafrost because of its obvious seasonal characteristics. This paper use the period deformation model instead of the traditional model to separate the elevation residual and atmosphere error better.(3) Analysis the results of D-InSAR with different time baselines and spatial baselines to set the correct time and spatial baseline threshold which can make the results of SBAS more robust.(4) Apply the advanced SBAS approach to get deformation time-series with a ENVISAT dataset composed by21acquisitions covering the study area. The results can provide some disaster prevention material for better construction and operation of the engineering in that area.