Diaphragm walling is a process of forming cast in situ reinforced concrete underground walls, from the surface, in sections (or panels). Cut-off walls are continuous semi rigid or rigid structures built below ground to impede water flow.
Stent's experience with diaphragm and cut-off walling is extensive, with projects ranging in size from 2,000 to 100,000 square metres, and from a few metres to as much as 55 metres deep. Stent is uniquely experienced in carrying out complex operations on restricted inner city sites, and was responsible for installing diaphragm walls in less than six metres of headroom in the re-development of Westminster Station on the Jubilee line extension.
Diaphragm walling is typically between 600 and 1,500mm in width with panels varying between 2.7 and 7m in length. Excavation is by grab - either rope suspended or hydraulically operated Kelly grabs. Walls can be installed as suitable for load bearing using reinforcement cages.
Cut-off walling differs from diaphragm walling in that the backfill material is normally a mixture of slurry and cementitious material, which forms a low permeability self-hardening mix.
