Prediction of groundwater pressures and uplift below excavations in tidal limits

Abstract A study to explain the mechanisms of cyclic pore pressure generation in ground below a tidal estuary is described: and how to predict these pressures caused by tidal fluctuations is explained. These estimates are used to examine uplift and instability to be avoided during construction inside deep marine excavations. Failure modes to be expected from predicted hydraulic pressures are reviewed and appropriate safety factors discussed. Results are presented for a range of in situ ground parameters. Critical levels within the excavations are used and the range of pore pressure relief required are presented for a particular safety factor.