The use of near-surface geophysics for monitoring slopes that affect transport infrastructure

Building upon relationships evident in the field, the development of laboratory-based petrophysical relationships that relate electrical resistivity to moisture content and soil suction directly is also discussed. 4-D ERT models were calibrated using these petrophysical relationships to provide insights into complex spatial and temporal variations in moisture content and soil suction. <br><br>Two study areas are considered here, enabling different controls on electrical resistivity to be examined.

The Ripley Landslide in the Thompson River Valley, British Columbia, Canada, threatens the serviceability of two national railway lines. Here, 4-D ERT models reveal complex hydrogeological pathways, providing new insights into the subsurface processes in an active, natural landslide. Freeze-thaw cycles also impact the subsurface resistivity here, which highlights the need to consider the impact of temperature when inferring changes in moisture content from ERT data.

The Old Dalby Railway Cutting in Leicestershire, United Kingdom, is also considered in this thesis. Subsurface changes in resistivity at this site across both wooded and grassed areas of the slope enable an improved understanding of hydrogeological pathways and allow examination of the use of ERT for assessing the influence of vegetation on subsurface moisture pathways and on slope stability. This thesis highlights the utility of geoelectrical monitoring for assessing slope stability in the context of moisture-driven landslides.

It aims to emphasise the benefits of 4-D geoelectrical monitoring and points towards the future incorporation of ERT monitoring in integrated decision support and early warning condition monitoring systems.<br>