Rock Face Stability Upper Beeding
Background
The site comprises a chalk quarry located near Upper Beeding, within the Southdown’s, West Sussex, and extends over an area covering c. 0.6ha. Activity within the quarry had been minimal over recent years, but proposals had been made to increase its yield. Southern Testing were requested to undertake a survey of the existing chalk walls and slopes to ascertain the risks associated with slope and face instability, and to recommend remedial action were necessary.
Investigation
The fieldwork comprised field mapping which included a discontinuity survey and the production of a geomorphological ‘hazard’ map. Information recorded on the hazard map included slope and face angle, areas that were infilled with lose chalk backfill, chalk bedrock, geological features, weathered profile, faults, and evidence of recent activity, e.g. areas of recent rock fall, loose chalk lumps on the face etc.
The information obtained from the discontinuity survey was used to undertake stereonet analysis to determine the risk of toppling, planar, circular, and wedge modes of failure.
Conclusions
According to our findings from the mapping exercise, field measurement and subsequent analysis, the site was categorized in terms of risk i.e. Low Risk- threat of minor injury, Medium Risk- potential of kinematic failure and causing harm, and High Risk- potential for kinematic failure and of causing significant harm.
The results were presented in a report and recommendations were given for reducing the risk of face/ slope failure to within acceptable levels. This included face regrading, construction of fences to collect chalk fragments that may fall from the face, restricting access to those areas that are at risk of failure, and banking soils against those faces at risk of failure.
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