Settlements of shallow foundations in granular soils due to rise of water table: a critical review

Settlements play a critical role in the designs of shallow foundations in granular soils. Future rise in water table below the foundation can produce additional settlements, which can threaten the integrity of the structure. The tolerable settlements of shallow foundations are generally small, in the order of 25 mm, and hence any such additional settlements have to be estimated with good care. A critical review of the current state-of-the-art for estimating settlements due to water table rise is presented. This includes analytical studies, laboratory model tests, field tests and numerical modelling studies. Terzaghi's(1943) hypothesis that settlement is doubled when the water table rises to the ground level is supported by some analytical studies and limited field data. Laboratory model tests suggest that the settlement increase can be significantly larger, especially at higher stress-levels. The numerical modelling studies carried by the authors suggest that linear elastic analysis supports Terzaghi's hypothesis and assuming a hyperbolic non-linear model suggests significantly higher settlements at higher stress levels, as observed in the laboratory model tests