GPS BASED ONLINE CONTROL AND ALARM SYSTEM (GOCA)

摘要

The contribution treats the GPS-based online control and alarm system (GOCA). The GOCA-System provides the online monitoring of movements of the earth's surface (e.g. land slide), geotechnical structures (e.g. safety of dams), buildings and the environment. The GOCA hardware is represented by an array of GPS-sensors and communication units set up in the monitoring area, and the GOCA-Software. The GOCA-Software controls the DGPS-array, collects and further evaluates the DGPS-data and sets alert. A long distance remote control of the GOCA system is enabled, and a well defined data interface allows to work with any DGPS-hardware on providing online the full capacities of a classical deformation analysis in a partition into stable and moving object points. The DGPS-array may either be occupied continuously or in the mode of a discrete occupation at different times. A network adjustment is performed for each interval of data collection, and the coordinate and covariance information are transformed into a specific reference system (e.g. the dam system) and referred to the stable point datum. The stability of the reference points is statistically controlled. Online filters are applied to detect and eliminate data errors and to smooth the time series, and predictions for the displacements and related functions are done. The basic version of GOCA performs online a so-called 'geometrical deformation analysis', meaning the mathematical modeling, graphical presentation, statistical testing and alerting based on the displacement field in space and time. A system analysis related deformation analysis however is directed to take the system equations into account. Based on the recorded displacements this is to be either modelled as a black box, a grey box or as a discrete system (e.g. finite elements method) in order to identify the deformation characteristics. The contribution treats a further development in system analysis direction. Finally an application example for GOCA is given: It deals with the control necessities of a special tailings pond situation. The slope of a 100 m high dump of processed material, coming from mining activities, shifts towards and into the active tailings pond. Movements of several mm/day at the foot of the slope due to successive failure and soil subsidence in the tailings area are observed. Besides other control systems, like pore water pressure measurements in the tailings body, these movements need a continuous online observation with GOCA in order to control the actual safety state of the complex system.