The GPS Single Epoch Algorithm For Deformation Monitoring Of High-rise Building

The safety issue of high-rise buildings is one of the most important issues in thefield of modern civil engineering construction. It’s often difficult to use conventionalmethods to do deformation monitoring of high-rise buildings because of its uniqueness.GPS has become the main method of the deformation monitoring of high-rise buildings,with many advantages. Usually, GPS RTK technology was used for solvingdeformation. Domestic scholars had proposed single epoch deformation monitoringalgorithm for small deformation monitoring according to its characteristics. Thismethod does not require cycle slips detection and repair, and it only takes one epoch ofdata to calculate deformation. The applying of single epoch algorithm in high-risebuilding deformation monitoring is significent.The paper systematically studied single epoch algorithm of GPS deformationmonitoring. The main research contents and results are as follows.1) Detailed elaborated the single epoch algorithm without whole cycle and singleepoch similar single difference algorithm. Pointed out that the single epochalgorithm without whole cycle is the same as the similar single differencealgorithm through derivation.2) The single epoch algorithm needs to use the priori coordinate to fix doubledifference ambiguity. It was derived that the single epoch deformationalgorithm can take advantage of the priori coordinates to fix double differenceambiguity if the deformation within the range of0.2cycles(in the mostunfavorable case).3) While using single epoch algorithm to do large deformation monitoring,ambiguity search is needed. In order to improve the efficiency of theambiguity search, a faster residual calculate method was proposed. Comparedwith directly solving equation, it can improve efficiency of about15%.4) In order to apply single epoch algorithm in continuous deformation monitoring,it was proposed to use high-frequency receiver and the algorithm through theanalysis of single epoch algorithm’s features. The feasibility of this approachis verified by experiment. 5) Multi-path effects are the main factors that affect the accuracy of single epochalgorithm. On the analysis of the mechanism of multi-path effects, using thefeature of multi-path effects relate to the signal direction, spherical harmonicfunction is proposed to estimate the multipath effects of various directions.The results can reflect the signal direction with serious multi-path effects.6) The wavelet transform was used to extract the low-frequency portion as themulti-path correcting model of the static deformation sequence because it isdifficult to correct multipath effects in deformation monitoring. The accuracycan be increased about30%after applying the extracted multi-path correctingmodel in subsequent data.7) The single epoch deformation monitoring program had been designed usingMatlab. The test data of one high-rise building was processed and achievedgood results.