none 10.1144/1470-9236/2000-53 Geological Society of London Geological Society of London 1881 30019070 67378 2024111903222000280 10.1144 2024-11-19T07:01:31Z 2007-11-13T17:08:49Z 29 Quarterly Journal of Engineering Geology and Hydrogeology QJEGH 1470-9236 2041-4803 06 07 2022 11 2002 35 4 N. Dixon 1Department of Civil and Building Engineering, Loughborough University, Loughborough, Leicester LE11 3TU, UK (e-mail: n.dixon@lboro.ac.uk) E. N. Bromhead 2School of Engineering, Kingston University, Penrhyn Road, Kingston upon Thames, Surrey KT1 1LQ, UK Factors controlling rotational landsliding in the unprotected London Clay coastal cliffs atWarden Point, Isle of Sheppey, Kent, aredescribed. Surveys of the landslides have been carried out at regular intervals since1971, and these are supported by an extensive subsurface investigation that included the installation of 56 piezometers. These studies have resulted in an understanding of the pore water pressures in the cliffs, including the role of undrained unloading resulting from slope formation, and pore pressures within the landslide mass ‘carried down’ the slope. The zone of depressed pore pressures is carried inland with the slope as the coastline retreats. Factors controlling the shear strength mobilized during first-time slides, and rates of movement, include geological control on the position of the slip surface and reduction in shear strength to close to the residual value along the basal section of the slip surface. This strength reduction results from stress relief controlled pre-failure deformations. A simple model is proposed to allow calculation of pore water pressures associated with the degrading slide mass. These have enabled back-analyses to be carried out which extend the residual shear strength envelope for London Clay to high effective normal stress levels, and explain the rate of re-activated slide movements. 06 07 2022 11 2002 327 343 10.1144/1470-9236/2000-53 1 10.1144/crossmark-policy www.lyellcollection.org true 2000-09-19 2001-07-05 2022-06-07 https://doi.org/10.15223/policy-002 10.1144/1470-9236/2000-53 https://www.lyellcollection.org/doi/10.1144/1470-9236/2000-53 https://www.lyellcollection.org/doi/pdf/10.1144/1470-9236/2000-53 https://geoscienceworld.org/qjegh/article-lookup?doi=10.1144/1470-9236/2000-53 Barton M.E.The preferred path of landslide shear surfaces in overconsolidated clays and soft rocks. Proceedings of the 4th International Symposium onLandslides Toronto September 16-21.3 1984. 75–79. CivilEngineering and Public Works Review 788 67 1972 Bayley, M.J.Cliff stability at Herne Bay. 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