Abstract
The present study provides a suitable GNSS positioning model for long-span bridge deformation monitoring and further improves the GNSS positioning performance using the multipath mitigation technique. An ambiguity-fixed ionosphere-weighted PPP-RTK model is constructed to provide real-time high-accuracy positioning service for long-span bridge deformation monitoring. In addition, a multipath model is established for GPS and BDS (GEO/IGSO/MEO) in the space domain for multipath mitigation. Elevation and azimuth of each satellite is recorded to compute multipath correction when the satellite appears in the same location. The results show that PPP-RTK can be well used for long-span bridge deformation monitoring. The multi-constellation multipath model can significantly improve performance. With the multipath mitigation method, PPP-RTK has obviously gained in the convergence time to reliably fix the ambiguities, as well as in the positioning accuracy and normal distribution characteristics of the observation residuals. We show bridge deformation monitoring results of the Hong Kong–Zhuhai–Macao Bridge for five consecutive days, where the PPP-RTK performance with multipath mitigation shows high positioning accuracy with fast convergence time. Moreover, our model is capable of identifying the high-frequency vibration and low-frequency displacement of the bridge. The natural frequency of 0.373 Hz in the vertical direction of the bridge under the typhoon Chaba excitation has been detected.