Stability of the Lower Greensand Escarpment in Kent.

An outline is given of the geological history of the Lower Greensand Escarpment in South East England up to and including the Pleistocene. A review is then made of historical and recent landslips that have occurred along the escarpment and a survey is included of the landslips that are currently visible. Details are given of the investigations into failures involving the Lower Greensand Escarpment at the Sevenoaks Bypass, Bayley's Hill and Ide Hill. These investigations established the widespread distribution of slip surfaces associated with large movements, superficial structures and deposits all of which occurred or were formed in a periglacial environment. Details of these discontinuities and structures are given and their implications on the stability of the escarpment are discussed. The field trials and measures adopted to overcome the difficulties that they presented to road works are detailed. The field trials included pore water pressures measurements which allowed: (1) the determination of the efficiency of counterfort drains as ground water lowering devices. (2) the comparison between the pore water response of embankment foundations with and without sand drain installations. (3) the comparison between in-situ and laboratory geotechnical properties