Irish peat slides 2006 – 2010

The purpose of this paper is to present a review of peat landslide events in
Ireland since 2003, when two significant events occurred. Since 2003, there have been at
least thirteen such events. Several of these events included more than one slide. It is also
likely that there have been unrecorded slides. It seems that there is an increasing
incidence of such events but they seem to occur in clusters with intervening quiet periods.
These clusters coincide with periods of intense rainfall. For many slides at least two
causal factors can be identified. Primarily these comprised intense rainfall but human
activities such as road construction and peat cutting also contributed to the slides.
Detailed geotechnical testing of the peat, including laboratory direct simple shear tests
(DSS), is reported for two of the slides. Back analysis of these two failures suggest that
the mobilised strength of the material in the failure surface is similar to that measured in
the DSS tests. However conventional geotechnical analyses need to be treated with
caution as they fail to account for the complex interactions in the sliding surface and in
particular the lubricating role of water.