Research Of Leveling Net Adjustment Under The Constraint Of GPS And The Vertical Deformation

Tianjin area is one of the serious settlement areas of ourcountry.The earliest precise leveling material began in the1950s. Aftermany transforms and encryption it has formed a complete precision levelnet (first class).Tianjin has accumulated rich data. However benchmarkproblem is a key and difficult subject that we should solved.The benchmark for the spread of stability and the error analysis ofthe vertical deformation precision cause important influence inconventional vertical deformation study. Benchmark problem to be solvedis a key and difficult task.In a long term, leveling depending on benchmarkto determine itself. So we need some assumption to determin the benchmarkwhen we determin the deformation(such as the single point datum, thepseudo inverse benchmark, the firm benchmark, flux, with the benchmarkand balanced "relative stability concept", and find out the relativestability reference point assume that their average face is motionless,etc). In fact all the standard points are changing all the time. Whateverwhich assumption we used, the leveling point movement will directlyinfluence the authenticity of the results.Especially analysisising thedynamic evolution. Therefore if we can get the real vertical crustmovement of the point and connect them with monitoring level net.It willseek the reiteration level point vertical movement rate without anyassumption. On the other hand, the current approach mainly uses the singlepoint benchmark, so the accumulative total error analysis of deformationis an important problem, also limit error accumulation is the problem thatwe cannot avoid. If we can use GPS continuous stand method appropriatlyto observation data as the restrictions on level measurement adjustment,and the above problems can be improved,at the same the dynamic changesof benchmark should be accuration.In this paper we have taken Tianjin ground subsidence data and TianjinGPS stations observation data. We collect and arrange lots of levelingobservation data.In the leveling net of first class there are52levelingline, The length of route observation level accumulate thousands ofkilometres in total; The time span from2006to2010; The measuring timeis on October every year, during this time Tianjin12GPS continuousobservatory will also be levelinged.The research programme of this paper is:first of all,arrangemeasurement data.Then analysis and compare the public points of twoyears. Seek the altitude differences of two years by using the indirect adjustment.Seeking the result again by using the GPS continuous changesrate as a constraint. In order to analysis the stability of the benchmark.With the new adjustment,the speed error of changes was improved. Themaximum and minimum speed error are better than single standard benchmarkmethod.Through the study, not only we accurate obtain the dynamic changingbenchmark results but also can use the results accurate to get changesof the variation of points. Therefore, this research is a very importantapplication for vertical crust deformation.