An investigation of two peat slope failures in the Wicklow mountains

Although peat slope failures have occurred in Ireland for many thousands of years their causal
factors and the triggering mechanisms involved are poorly understood. A particular barrier to
quantitative assessment of the risk of failures is the lack of knowledge of the geotechnical
properties of peat and its role in failures. In order to advance the understanding of these issues
case history data is invaluable. This paper describes a case study from the Wicklow
mountains where a desk and remote sensing based study was used to identify peat slope
failures. Subsequently detailed field studies were carried out at two failure locations. It was
found that although the full causal factors at the time of failure are unknown, a common
factor was that the failure took place in a zone of highly decomposed and relatively low fibre
content peat. A revision of the standard test method for fibre content for use in peat soils is
proposed.