Rock and Slope Stability Survey and Hazard Assessment

Southern Testing have recently completed a survey examining the face and slope stability within an existing chalk quarry in the Southdown’s National Park.  It is proposed to substantially increase the yield of the quarry, and a survey of the existing chalk faces and slopes was requested to assess the risks associated with slope and face instability, and to recommend remedial action were necessary.

The fieldwork comprised a discontinuity survey and production of a geomorphological ‘hazard’ map’. The discontinuity survey involved measuring the dip, dip direction, persistence, infill, dilation, seepage, and roughness of joints, faults, bedding planes. The hazard map involved carrying out a visual survey of the slope and faces, identifying any evidence of recent failures or any evidence of potential future failure i.e. loose chalk bocks, as well as slope and face angle and direction, areas that had been infilled with loose chalk backfill, chalk bedrock, geological features, weathering profile, faults, etc.

The information obtained from the discontinuity survey was used to undertake stereonet analysis of the chalk faces, which was used to analyse the risk of toppling, planar, circular, and wedge modes of failure.