Astudy On Key Technology Of High Precision GPS Monitoring For Geological Hazard

China is one of the most serious areas of geological hazard in the world. In order to realizethe evaluation, prediction and early warning of geological hazard, it is an urgent scientifictask to monitor the geological hazards such as landslide, collapse, debris flow, groundsubsidence and fissure with high precision and grasp the deformation regularities andcharacteristics of different geological phenomenon and geological hazards.At present, GPS positioning technology has been widely used in the field of geologicalhazard monitoring. But there still has many unsolved key technical problems on how torealize high precision and fast positioning, such as the elimination and correction of GPSobservation error at special environmental conditions, the quality inspection and judgment ofGPS observation data, the determination of the monitoring precision indexes for differentgeological hazards, the GPS data processing scheme, the precision and availability of GPSPrecise Point Positioning technology, the applicability of GPS dynamic positioningtechnology, and the key technical problems on the construction and implementation of GPSreal-time deformation monitoring system, etc.Focusing on those problems and combining with the implementation of several geologicalhazards monitoring projects, the theory, key technology and methods were studied anddiscussed in this dissertation by aiming at how to implement the high precision and rapidpositioning with GPS technology. Then some important results were obtained. Thoseinnovative and beneficial results can be used to guide the practical application for geologicalhazards monitoring by using GPS technology.The main research work and results of this dissertation are as follows:1. Aiming at the influence of observation error on high precision GPS positioning, theinfluence rules of the satellite ephemeris and tropospheric delay error on highprecision GPS monitoring results were discussed, and some treatment measures wereput forward in the high precision GPS baseline vector solving when the length ofbaseline is longer enough or the altitude difference between two stations is biggerenough, such as adopting the precise ephemeris and tropospheric delay correction models, etc.2. In order to solve the problem of how to estimate the quality of station observationenvironment and the performance of GPS receivers in high precision GPS monitoring,a new method was proposed to test the performance of GPS receivers by using thetime series of which was the difference betweenMP1andMP2calculated by theraw observation data. This new method can be used to rapidly test and judge themeasurement performance of the GPS receiver in high precision GPS positioning.3. The applicability of PPP technology was discussed in the monitoring of geologicalhazard such as land subsidence with a wide range and slow movement speed. Throughthe processing and analysis of monitoring data in one region which had a wide rangeland subsidence, it is detected that the internal accordant precision of GPS PPP can beachieved about5mm and the external accordant precision can be achieved about20mm. This indicates that the static PPP technology can be totally used in thedeformation monitoring of geological hazard with a wide range and slow movementspeed by the precision of centimeter after the fine error correction models are adoptedto correct the error which has an effect on GPS positioning.4. In order to improve the convergence speed, positioning precision and reliability, thisdissertation proposed a new PPP algorithm based on base station correct informationand epoch difference without ambiguity. The time consume of convergence can begreatly shorten and the deformation information at every single monitoring point canbe quickly gotten independently by using this new algorithm in a wide area.5. In order to reduce the hardware cost of GPS precise point positioning, the keytechnology and methods of high precise positioning by using single frequency GPSreceiver were studied and discussed in this dissertation. And a kind ofsingle-frequency PPP algorithm based on the raw observations was presented in thisdissertation. By this algorithm, the ionospheric delays are corrected efficiently bymeans of adding the ionospheric delay prior information and the virtual observationequations with the spatial and temporal constraints, and they are estimated as theunknown parameters simultaneously with other positioning parameters. Thecalculation results indicate that the convergence speed and stability of the new algorithm are much better than the traditional PPP algorithm, and the positioningaccuracy of about2-3cm and2-3dm can be achieved respectively for static andkinematic positioning with the single-frequency observations’ daily solution. Thisnew PPP algorithm can be completely used in the deformation monitoring ofgeological hazard with a wide range by the centimeter or decimeter precision.6. Through the discussing of relationship between landslide monitoring precision,repetition period and speed, some key problems such as precision, scope andqualification of the GPS rapid positioning technology were discussed in the dynamicdeformation monitoring for landslide hazard. Examples and the results indicate thatthe RTK technology, GPS single epoch positioning technology and real-time PPPtechnology can be used in the real-time dynamic deformation monitoring of landslidewith medium speed (level4) or above.7. Based on the study of the key technology and methods in high precision GPSmonitoring for geological hazard, a kind of monitoring technology route integratingthe GPS static with dynamic positioning technology was proposed in this dissertationand the GPS real-time dynamic monitoring system on Zengziyan dangerous rockmass was established. This monitoring system can realize the three-dimensionaldynamic deformation monitoring for dangerous rock mass automated at all weatherconditions. Then the timely and accurate warning for dangerous rock mass can berealized. And the positioning precision of about5mm and10mm can be achievedrespectively for horizontal direction and vertical direction.