Research On Key Technologies Of Quasi-real-time Monitoring Of Geological Deformation Based On Ground-based Radar Interferometry

Geological disasters occur frequently in China,among which landslide is one of the most serious disasters,which brings huge losses to people's lives and property safety.As landslides are difficult to be detected by naked eyes and traditional means due to the characteristics of "high position and concealment",it is of great practical significance to carry out the risk monitoring and early warning of geological disasters as well as the post-disaster emergency monitoring.The ground-based radar interferometry technology doesn't need investigators to go deep into the location of hidden dangers and precarious situations of geological disasters,which can not only observe the deformation of geological bodies from multiple dimensions and angles,but also obtain the quasi-real-time continuous deformation features,thus detecting the development trend of disaster-forming bodies.Although the ground-based radar interferometry technology has advantages such as short revisit periods and high monitoring accuracy,there are still some scientific and technical problems to be resolved.Based on the ground-based radar interference technology,this paper focused on the need for geological disaster emergency landslide deformation information acquisition.It mainly studied the key technologies used by ground-based radars to quickly obtain reliable deformation information,including atmospheric delay phase correction and quasi-real-time processing technology.The specific contents are as follows:(1)The commonly used atmospheric phase correction methods and their applicability were analyzed in detail.An iterative decomposition method based on the distance elevation model was introduced,which can be used to correct the atmospheric turbulence changes.The iterative decomposition model further decomposed the static and dynamic atmospheric phases into stratified and turbulent phases so as to overcome the failure of the distance elevation model due to the rapid atmospheric changes without the help of GNSS or external meteorological data,thus improving the accuracy of the geological body deformation monitoring.(2)A processing method suitable for the quasi-real-time monitoring of ground-based radars was designed based on the concept of the small baseline set of spaceborne interferometric radars.It mainly connected adjacent units through common coherent pixels to form the merging unit.Then it calculated the optimal solution of the merging unit by least squares.In addition,the timeliness of the quasi-real-time monitoring of sub-units was also analyzed.The phase unwrapping error rate and accuracy were established as the evaluation indexes of the quasi-real-time processing.The quasi-real-time monitoring algorithm of sub-units can overcome the limitation of the deformation figure delay and provide strong technical support for emergency monitoring.(3)Taking Xuyong and Baige landslides as examples,this paper tested the above algorithms and demonstrated their applications based on the construction of the high-accuracy quasi-real-time deformation monitoring technology framework of ground-based radars.The iterative decomposition method was used to correct the atmospheric errors of Baige landslide monitoring,verifying the effectiveness of the iterative decomposition method;the quasi real-time deformation monitoring of the two landslides was carried out to evaluate the phase unwrapping error and accuracy,thus verifying the reliability and accuracy of the real-time processing algorithm of sub-units.