Sustainable landslide stabilisation using deep wells installed with siphon drains and electro-pneumatic pumps

摘要

In the winter of 1994/95,a major accelerated reactivation of a pre-existing landslide occurredat Castlehaven,Isle of Wight,UK. This event was a consequence of both coastal erosion and high groundwaterlevels. If left unchecked this landslide had the potential to evolve further causing direct and consequentialfinancial losses estimated to be (f)20 million (at 2004 prices). To address the problem of landsliding and toreduce the risk to public safety,property and infrastructure,a coastal protection and landslide stabilisationscheme was implemented. The slope stabilisation scheme included the use of 151 deep pump drainage wells,installed with 125 siphon-drains and 35 electro-pneumatic pumps,to reduce winter groundwater levels to theequivalent summer levels where movement is substantially reduced,thus improving landslide stability and at thesame time protecting valued environmental assets. This paper describes the substantial advantages,in terms ofsustainability,provided by the adopted design approach and by the type of drainage equipment used.