SLOPE STABILITY MONITORING
system typically comprises three elements : sensor nodes , a wireless communications platform ( WCP ) and a user portal . Sensor nodes measure a range of parameters , the most widely used being high-precision tilt sensors which measure rotation about the horizontal axis . Incorporating triaxial sensors , these instruments can be commissioned at any orientation on any surface . Other widely used sensors are crack / displacement gauges , optical displacement sensors ( ODS ) and a family of vibrating wire-based devices including piezometers , strain gauges , load and pressure cells , as well as in-place inclinometers , temperature and moisture sensors . A monitoring array can therefore be configured to detect movement as well as the potential geotechnical causes of that movement .
A WCP transmits data from the sensors to a gateway / monitoring hub before collating and transferring data to the internet or directly to a private network owned by the client . Most mine applications require transmission over distances exceeding a kilometre and therefore use a long-range LoRaWAN radio platform radio platform . Senceive ’ s GeoWAN technology , for example , has the power to transmit through physical obstructions , enabling integration of sensors from various different installations or physical locations into a single , unified network . In this way , data from instruments installed in boreholes can be correlated with data from sensors installed on pit walls , tailings dams , railway track or buildings . From the gateway or monitoring hub the options for getting the data to the outside world are restricted only by the available infrastructure . The simplest option may be the cellular network ; alternatively , Wi-Fi or ethernet may be used if suitable infrastructure is available .
A user portal enables viewing and interaction with the monitoring output . Most remote monitoring setups offer a custom viewing tool and also offer delivery of data in formats compatible with industry standard management software such as Leica GeoMoS , Trimble 4D Control , Topcon Delta Watch , Mission OS , VDV , Geoscope , Eagle . io , Calyx OMS and many more . Varying degrees of remote interaction are possible . Some platforms provide functionality enabling users to change configuration settings such as sampling frequency without site visits – a significant safety and cost benefit where site access is constrained .
While sensor nodes have an independent battery life of many years , the gateway that collects sensor data and forwards it to the client requires a power supply . The most straightforward option is to use a fixed electrical ( mains ) power supply where available . At most mine sites it is possible to power the gateway from a solar panel which will charge the internal battery during daylight hours . In situations when this approach is not possible ( underground , or at latitudes with few daylight hours in winter ), external batteries alone may be used , but these will require periodic replacement .
Installing a wireless monitoring system is relatively straightforward and can usually be done without requiring specialist surveyors or monitoring experts . Brightwell comments : “ The ramifications of slope failure can be significant in terms of safety , environmental and commercial risk . Reliance on any one system of inspection , survey or monitoring is inherently flawed . A combined approach is generally regarded as more reliable in terms of detecting the early signs of failure and transmitting an alarm . Wireless monitoring is therefore a useful addition to the slope management toolbox and works well alongside remote sensing radar arrays and LiDAR as well as targeting resources for visual and topographic surveys .”
A key element is system automation . Most systems can transmit automated alerts to nominated stakeholders if a pre-set trigger level is breached , but more sophisticated systems can do considerably more . The degree of automation that can currently be achieved is dependent on a number of factors , including the bandwidth of the communications platform . Platforms operating in the ( relatively high frequency ) 2,400 to 2,485 MHz band can be configured to change their behaviour in response to events . The Senceive FlatMesh™ platform , for example , can be
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