GNSS/LPS Based Online Control and Alarm System (GOCA) - Mathematical Models and Technical Realization of a System for Natural and Geotechnical Deformation Monitoring and Hazard Prevention

Abstract

The research and development project GOCA (GNSS/LPS based Online Control and Alarm System) applies GNSS as well as classical local positioning sensors (LPS), such as e.g. total stations, for a real-time deformation monitoring. The GOCA system may be set up as an earlywarning- system for natural hazards (landslides, volcanos) and also for the monitoring of geotechnical installation and buildings (mining, tunneling activities, bridges). The GOCA system consists of GNSS and LPS sensors, which are set up in the monitoring area as a permanent array or as a mobile monitoring system. The GOCA hardware-control and communication software modules collect, in different kind of communication modes, the GNSS/LPS data in a user defined sampling rate. The GOCA deformation-analysis software is responsible for a further processing of that data in a three steps sequential adjustment procedure. Both least squares and robust estimation techniques (L1- norm and other bounded influence M-estimators) are applied. A first focus is set on the robust online displacement estimation, statistical testing and alarm setting. Further the algorithmic scheme of a L2- and a robust L1-norm Kalman filter is treated, which is applied in the GOCA system for the estimation of the object-point state vector of displacements, velocities and accelerations. The further development of the deformation analysis concern the integration of further parameters (e.g. material parameters and damage models) as well as of additional geotechnical sensors (e.g. strainmeters) and lead to system analysis based approaches. Here FEM-based approaches for static and dynamics processes are proposed as appropriate models. Typical project applications are shown as examples for the GOCA-system.