GNSS Real-time Relative Positioning Technology And Its Application In Landslide Monitoring

The frequent occurrence of geological disasters in our country is one of the most serious injuries and property losses caused by the landslide.Before the landslide disaster,the landslide body needs to go through a course from slow displacement to collapse and mass change,and how to master the small deformation of the landslide body before the collapse scientifically and effectively has a very significant practical significance in our country.With the independently designed and constructed BeiDou satellite navigation system in our country put into use formally,our country GNSS users have been able to receive the navigation,positioning and timing services mentioned by the four global satellite navigation systems from GPS,GLONASS,GALILEO and BDS.High-precision GNSS positioning service has been widely used in landslide deformation monitoring.And in recent years,with the rapid development of real-time communication technology,the advantages of real-time GNSS are more prominent than other measurement and monitoring methods.Therefore,Landslide monitoring based on high-precision real-time positioning has attracted more and more attention.In the GNSS high-precision positioning technology,relative positioning can eliminate or significantly reduce most systematic errors based on the principle that the systematic errors experienced by two stations during synchronous observation are substantially the same,so that the system errors can be more quickly and accurately Get high-precision positioning results,has become the main mode of operation for high-precision real-time positioning.Based on the relative positioning theory of GNSS,this paper focuses on key technologies such as cycle slip detection,accurate ambiguity fixation and joint localization of multiple systems under the condition of real-time landslide deformation monitoring.Based on the simulated displacement platform,The ability to monitor the decimeter-class displacement under medium-baseline conditions.Meanwhile,the GNSS real-time relative positioning technology was applied to the JingYang landslide.The long-term monitoring results were compared with the total station monitoring sequence to verify the application of GNSS real-time positioning technology Effectiveness of landslide deformation monitoring.The main contents and conclusions of this paper are as follows:1.Aiming at the problem of cycle slip detection in relative positioning of carrier phase of GNSS,this paper deeply analyzes two kinds of double-frequency cycle jump detection methods,such as MW combination and LG combination,pseudo-range phase and no geometric phase.Difference threshold for real-time cycle jump detection,insensitive cycle jump and other characteristics.Using BDS,GPS measured static and slow dynamic data to verify the performance of different cycle jump detection methods.The results show that all the methods have insensitive cycle slip,but the combination of multiple detection methods can significantly reduce the possibility of cycle slip estimation.Meanwhile,the combination of three-frequency non-geometric phase satisfies the requirement of cycle slip detection under the condition of slow-moving.2.The related theories of ambiguity parameter estimation and LAMBDA ambiguity resolution are introduced in detail,and the most important Z transform matrix construction method in LAMBDA is deduced.Aiming at the problem that the ambiguity is difficult to be accurately fixed in complex conditions,Based on the experimental data,this paper proposes a new method of partial selection of the ambiguity,which is more suitable for the real-time deformation monitoring of landslides in complex conditions-the comprehensive screening method.Based on the measured data,the method proposed in this paper is better verification.3.At present,when people design multi-system combination positioning programs,the combination method usually used is based on the coordinate estimation domain,the normal equation domain and the observation equation domain.For the latter two,people tend to think that they have the equivalence Lack of related analysis of their similarities and differences.Based on the analysis of different method function models,this paper deduces that the two methods are equivalent under the condition of static solution,while the combination of dynamic condition observation equations is more rigorous and the result is better.Based on the measured results Short baseline data to verify the above inference.4.In order to verify the effectiveness of GNSS real-time localization in landslide monitoring,the landslide sliding process was simulated by displacement platform and the deformation process was monitored by GNSS baseline with short and medium distance(1KM,60km).The experimental results show that the short-baseline and medium-baseline landslide real-time deformation monitoring can effectively monitor the displacement of the landslide,but the mid-baseline is subject to its own observation accuracy,and the monitoring results will appear centimeter-level fluctuation.Therefore,For centimeter level landslide displacement monitoring reliability will be greatly reduced.Based on the monitoring project of loess landslide in JingYangMiaoDian,the 241-day GNSS real-time relative positioning technology is compared with the high-precision total station monitoring data.The results show that the results of GNSS real-time relative positioning technology monitoring results and total station monitoring results are in the E,N and U,respectively.The differences of long-term monitoring results in three directions of E,N and U were(in millimeters): 2,0 and 1 respectively;the maximum differences in the monitoring process were : 3,6,9.Therefore,GNSS real-time positioning technology fully meets the precision requirements of landslide monitoring.