Landslide Assessment, East Devon

Ruddlesden geotechnical were called to site, following a prolonged period of uncharacteristically intense rainfall, to assess the likely cause and ongoing stability of a recent landslide.

The slide was observed to exhibit largely typical earth/ debris flow characteristics, with some minor rotational failure at the crest of the slide. It was surmised that, fundamentally, the slide was a consequence of the underlying geology, which essentially comprised a succession of Lower Cretaceous Upper Greensand resting above Blue Anchor/ Branscombe Mudstone Formations, and the intense/ prolonged rainfall which had preceded the slide.

However, it was also noteworthy that evidence of anthropogenic activity (human interference) was observed within the immediate area of the landslide. These included a domestic surface water outfall pipe discharging at the crest of the slope, and evidence of tree felling within the slide. The additional water introduced to the slope from the discharging water pipe, the reduction in natural transpiration of groundwater as a result of tree felling and associated loss in mechanical strength through degradation of the root system were all identified as significant contributory factors towards the slide.

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Landslide Assessment, East Devon image

Landslide Assessment, East Devon image