Great to see these two contiguous jacked caisson shafts successfully completed by Joseph Gallagher Limited in Tangmere, West Sussex.
The shafts were sunk through Lambeth sands leaving a thin Clay cill above the Chalk beds, holding a pressurised aquifer. We worked together with JGL, conducting pumping tests and additional boreholes to establish the complex groundwater regime and ground conditions, and so sink the shafts through a mix of ‘dry and wet caisson’ methods, depressurising and managing the running grounds ahead of the shaft.
The shaft base levels were adjusted to adapt to variable ground conditions on site, providing toe-in to the clay to balance piping from the hydraulic gradient whilst maintaining a sufficient depth of clay cill to avoid basal heave from the lower pressurised chalk aquifer.
Thanks to the entire Joseph Gallagher Limited team for a challenging and enjoyable project!
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