Published Thu 20th Jul 2023
In the United States, the annual cost of landslides exceeds $2 billion. Slope failure mitigation measures can reduce the impact of these events and save lives. Numerous factors contribute to slope failure risk, such as heavy rain, vegetation removal and earthquakes, in combination with the growing number of people living in affected areas. It is vital to understand geologic hazards in order to mitigate slope failure risk, and the use of intelligent monitoring solutions such as the Senceive InfraGuard system can save infrastructure, property and human lives.
In this context, risk can be defined as the probability of a damaging event taking place,and key considerations include an assessment of the impact of that event and the amount of risk that an organisation are prepared to accept. Slope failures may appear to be entirely unpredictable, but with appropriate modeling supported by field monitoring, early signs can be spotted and advance warning issued. This early warning can help reduce disruption and danger, and may even enable mitigation measures such as slope stabilization measures to prevent the failure of an unstable slope.
Because geohazard events such as slope failures are hard to predict, mitigation measures have historically been reactive. For decades, visual observations and manual monitoring techniques were used evolving later on into geotechnical and structural automated systems that allowed the development of proactive strategies based on data collected regularly from the field. From there, critical knowledge was built around sensor type, spatial deployment, data acquisition frequency and in recent years, further developments have been allowed by the rise of computer science, bringing wireless technology and intelligent monitoring solutions to the forefront of slope failure mitigation.
These “intelligent monitoring systems”, like Senceive’s InfraGuard™ solution, are based on the use of wireless “MEMS” tilt sensors installed on stakes driven into the ground allowing the detection of relative movement of a slope. The sensors take readings in a defined interval and are triggered by a sudden event leading to additional readings, while also activating adjacent sensors and increasing the corresponding monitoring frequencies. The system can also be combined with a camera, which is also triggered by this event and allows visual inspection remotely.
With an increasingly volatile climate, the challenges of safely maintaining and operating infrastructure are set to grow, making the need for automation and intelligent monitoring systems ever greater.
The InfraGuard™ solution is built around a network of intelligent sensors that communicate with the internet via a mesh-networked wireless communication platform (FlatMesh™). This was developed over the last decade by Senceive with its roots traceable to research at University College London initiated in 2005. A version launched in 2013 was the first to incorporate edge computing and built-in intelligence in the sensor nodes. By 2015, variable reporting rates, automated event triggering and an integrated camera were added, along with improvements to power consumption giving a typical node life of more than a decade between battery changes.
Intelligent processing of data at the sensor node and automatic decision-making capability has benefited remote geotechnical condition monitoring applications. Sampling is normally set at fixed intervals of 15 to 60 minutes, but this is automatically accelerated as thresholds are breached in order to send alerts in near real time. The detection of movement will also trigger other nodes in the network to wake up and the camera node to capture an image. Where critical conditions arise, the gateway automatically allows the override of communication protocols to enable immediate data transmission to the server.
The system employs an adjustable series of alerts based on the scale of movement recorded. These are summarized in Figure 1 below, together with the dynamic reporting rates which provide increased sampling as the level of concern grows.
Figure 1. Left: reporting rate versus sensor value: Right: alert thresholds and dynamic reporting rates
For the monitoring system to be qualified as “Intelligent”, it needs to encompass a few key attributes. The algorithm is based on the sensor output, sensor precision, and repeatability and comprise the base layer of the system. In addition, low power consumption communication protocols quickly transfer the information from the sensor to the end user, allowing for reliable and long-lasting installations.
It is important to note some of the system limitations. At present, the only sensors that can be used to automatically adjust their frequency and trigger cameras are triaxial tilt sensors. Other sensors can, however, be incorporated into the same wireless monitoring program, including optical displacement sensors, crack sensors, vibrating wire sensors, and other integrator nodes that can provide additional information in relation to the slope. Additionally, it is not possible to operate an intelligent monitoring system on the long range LoRa point-to-point network that is used by much of the wireless monitoring industry due to lack of bandwidth and issues relating to synchronisation and communication.
To find out more about slope failure mitigation and intelligent monitoring, get in touch with us or fill out the form below today for regular insights.
