The Thames Water Ring Main at Kew is an approximately 2.5m diameter concrete segmental lined tunnel that passes obliquely right beneath the new 8-storey Heritage Walk apartment blocks. The ring main is sensitive to ground movement because the water within is under a low pressure and may leak if the tunnel became excessively distorted. For the development to receive planning permission, its piled foundations needed to be kept clear of an exlusion zone around the tunnel (which created a complex foundation geometry) and the resulting settlement, rotation and distortion of the tunnel needed to be kept within tight limits.

A 3D FEA model of the proposed foundations, ring main tunnel and surrounding ground was used to predict tunnel displacement and show that the tight limits would be satisfied leading to the award of planning permission.

Highlights

• Detailed study of the ring main's construction and sensitivity to ground movement at this location.

• 3D FEA model of complex geometry including the pield foundations around the exclusion zone and the ring main passing obliquely beneath the site.

• Simulation of demoliton of existing buildings and construction of proposed development.

• Prediction of tunnel settlement, rotation, curvature, diametrical distortion, tensile strain and hoop force shown to be within acceptable limits.

• Planning permission for the development granted.

Intrested in how FEA can predict the settlement of tunnels in urban areas? Read this case, here.