Assessment of Landslides using Acoustic Real-time Monitoring Systems (ALARMS)

Slope failures, worldwide, cause catastrophic consequences, resulting in many thousands of deaths each year; damage to civil infrastructure costing billions of pounds; displacement of people from their homes, and the breakdown of basic services such as water supply and transport.

Development

Installation of ALARMS sensors on an active landslide site

Installation of ALARMS sensors on an active landslide site

A prototype acoustic emission device invented at Loughborough University has been re-engineered by BGS using state-of-the-art, low cost, miniaturised acoustic sensors and integrated with wireless networking capability (GSM) to provide early warning of slope instability.

The ALARMS sensors are permanently installed and transmit a real-time SMS text message when the acoustic soil activity reaches a pre-defined threshold.

Imminent landslides are normally accompanied by increased acoustic emissions levels (high-frequency stress waves) due to inter-particle soil friction and displacement.

ALARMS uses a steel tube called a wave guide to conduct the signals out of the ground. The steel tube is placed in a borehole in the ground that is filled with sand or gravel. The sand and gravel produces more energy when moved than the surrounding soil, which makes the signal easier to detect. The device also detects high-frequency waves of around 20–30 kHz.

Lower frequencies lose less energy and are easier to detect but invariably include background noise from other sources. Our results have demonstrated how the acoustic signal produced by the gravel can be related to the speed and size of movement in the ground, regardless of the type of soil.

The device has been performance tested and demonstrated at an active landslide site, in Yorkshire, UK.

A business plan has been developed to enable the commercial exploitation of the technology. The plan includes a long-term vision, cash-flow projections, and marketing strategy to attract inward investment by licensing or spin-out.

The wireless telemetry and re-engineering required for ALARMS drew heavily on BGS's expertise in developing an Automated time-Lapse Electrical Resistivity (ALERT) system for monitoring the stability of both natural landslides and engineered structures like dams, embankments and hydraulic barriers.

Acknowledgments and awards

The research was funded by a joint EPSRC follow-on grant to BGS and Loughborough. The project won the University Enterprise Award in 2010 for being a practical low-cost innovation that could significantly reduce loss of life in developing countries.

Contact

Philip Meldrum
Project Leader
British Geological Survey
Tel: +44 (0)115 936 3374
E-mail: Philip Meldrum

Prof Neil Dixon
Geotechnics Group Leader
University of Loughborough
Tel: +44 (0)1509 228542
E-mail: Prof Neil Dixon