Ground-penetrating radar and badger setts
Journal
Journal of
Engineering Geology and Hydrogeology, Vol 36, No 2, 1 Jan
2003, pp. 143-153(11)
Authors
Nichol D.; Lenham J.W.; Reynolds J.M. from NEWTRA
Geotechnical Group, Wrexham, and Reynolds Geo-Sciences Ltd, Mold,
Flintshire
Abstract
Application of ground-penetrating radar to
investigate the effects of badger setts on slope stability at St Asaph Bypass,
North Wales
At the St Asaph Bypass, surface
cracking developed along the crest of a modern highway cutting, above a cluster
of badger setts excavated in the sandy soils of the cutting slope. This prompted
concerns about the extent of the underlying tunnel systems and the possible
existence of deep cavities lacking surface expression that might cause a
potential slope instability problem. The full threat posed to the integrity of
the cutting and to the safety of road users remained uncertain. In addition,
intrusive investigations were deemed inappropriate and a non-invasive solution
to the problem was required.
Ground-penetrating radar was used along a 50 m stretch of the cutting to
determine the full extent of the badger setts beneath the surface. The
geophysical survey identified 324 m of tunnels and demonstrated that the tunnel
network was generally shallow (c. 0–2 m). Pronounced radar reflections
characteristic of air voids were identified in the data and interpreted as the
badgers’ access tunnels and living and nursery chambers whereas the more subdued
features were interpreted as collapsed and abandoned diggings. This case history
illustrates the benefits of using ground-penetrating radar to provide an
understanding of slope stability and local ground conditions in areas of
environmental sensitivity when non-intrusive investigations are required to
provide reassurances in relation to public safety.
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