Centrifuge model tests on doubly propped embedded retaining walls in overconsolidated kaolin clay

A series of tests on model diaphragm walls embedded in an overconsolidated clay was carried out at the London Geotechnical Centrifuge Centre, The wall s were propped at the crest at the start of excavation and, following the s imulation of excavation, were immediately propped at formation level. A ret ained height of 10m was modelled in all tests, and the depth of embedment b elow dredge level varied between 5 m, 10 m and 15 m, A 'softer' constructio n sequence was also investigated, with excavation to 5m below the retained surface taking place prior to the installation of the crest-level prop. The effect of pre-excavation lateral earth pressure was also investigated. The test results show that an increase in embedment depth will lead to an incr ease in wall bending moment and a reduction in bottom prop load. There is n o real advantage in terms of limiting ground movements in increasing the em bedment depth without also increasing the wall stiffness.