The Franklands Village landslide

Abstract

Between 23 December 1993 and 5 January 1994 a major landslip movement developed in Franklands Village which is situated on the eastern side of Haywards Heath, West Sussex. The approximate Ordnance Survey map reference is TQ 342/236. The site of the landslide is set on the eastern slopes of a north-south trending valley. The existing development comprises blocks of two-storey fiats and semi-detached houses. The development for the Franklands Village Housing Association (FVHA) was constructed in the 1930s. A development comprising a block of two-storey sheltered housing (Charles Bennett Court) was constructed by the Hanover Housing Association between 1991 and 1992, on the higher valley slopes to the southeast of the landslide. Southern Testing Laboratories Limited (STL) were called in by Messrs K. A. Marshall & Partners, Consulting Engineers to the FVHA, to investigate cracking and foundation movement that had been developing in the Franklands Village properties during December 1992. In general terms the valley slopes fall towards a small stream, towards the northwest at overall slopes of between 13 and 16° . Terracing, carried out to facilitate the initial development, steepened locally to between 30 and 45°. An investigation comprising hand-excavated trial holes, shell and auger boreholes (using a specially adapted restricted access rig), piezometers, slip indicator and monitoring of surface reference stakes, laboratory testing and geological and engineering analysis was undertaken by STL between January and April 1993. The solid geology comprises the Upper Tunbridge Wells Sands at the crest of the slope, overlying the clays of the