Fibre Bragg grating and Brillouin optical time domain reflectometry monitoring manual for the Ripley Landslide, near Ashcroft, British Columbia

Abstract

An international multi-year project is investigating and monitoring the Ripley Landslide, 7 km south of Ashcroft, British Columbia. The aim of this collaborative work is to better understand and manage landslides along Canada's western railway corridor. From 2013 to 2016, the China Geological Survey (CGS) and Geological Survey of Canada (GSC) collaborated to test and evaluate experimental fibre Bragg grating (FBG) and Brillouin optical time domain reflectometry (BOTDR) technologies on an active landslide for the first time in Canada. Open File 8258 describes the operational procedures for these monitoring systems. FBG and BOTDR monitoring systems were installed on a lock-block retaining wall that separates the Canadian National (CN) and Canadian Pacific Railway (CP) tracks. This vital component of railway infrastructure crosses the southern extent of the main slide body; and was monitored with the aims of better understanding the deformation mechanisms and potential triggers for sudden movement; and managing the risks associated with railway operations. Monitoring data was processed on site then accessed by wireless transmitter from remote terminals at the CGS and GSC offices. Results, discussed in the context of interpretations from other physical surveys of the landslide, provide new insight into the nature and distribution of surficial earth materials, their stratigraphic relationships, internal structure of the landslide, and structural integrity of critical railway infrastructure. This study demonstrates that optical fibre sensing real-time techniques are viable, cost effective monitoring methods that can ensure the safety and security of the railways, thereby reducing risks to national public safety, the environment, natural resources and international economies.