Water Table Correction Factors for Settlements of Shallow Foundations in Granular Soils

Shallow foundations are designed to limit settlements within tolerable limits. Additional settlements produced by the rise of the water table due to rain or floods can jeopardize the integrity of the foundation. This paper proposes a rational method, based on strain influence factors, to predict the additional settlement produced by the rise of the water table on a footing resting on sands. The proposed method was validated using extensive laboratory test data, where model footings of five different shapes were loaded in sand placed at two relative densities, and the water level was raised from the bottom while the additional settlements were measured. The clean sands used in the tests were such that there were negligible capillary effects. Separate tests were carried out to demonstrate that the capillary effects were insignificant. The proposed method can be used as the basis for further studies that incorporate the effect of grain size distribution or the effects of water table fluctuations on additional settlement. (C) 2014 American Society of Civil Engineers.