4. Continuous Data - Frequent sampling Frequency of sampling is a key factor in establishing an acceptable level of confidence that a significant event will be detected. An approach based on scheduled visual inspections or surveys may yield high quality data on asset condition, but will typically be conducted too infrequently to reliably detect a dynamic defect such as a failing slope. A growing number of automated technologies are available that can provide frequent updates based on remote instruments. Techniques for slope monitoring include INSAR, automated total stations and wireless condition monitoring as well as geotechnical instruments that can be left in boreholes to monitor parameters including groundwater and vertical and horizontal movement. For structural health monitoring there are even more options, including instrumentation to monitor movement, engineering parameters such as
stress and strain, as well as changes in chemical and environmental properties. Technologies include accelerometers, acoustic emissions sensors, fibre optics, vibration sensors and tilt meters. Most of the automated techniques operate on the basis of intermittent sampling and reporting. Some can transmit their data automatically, whereas others require a person to visit site and download results. They do not, therefore, truly address the need for high frequency or continuous sampling to detect sudden events.
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