Infiltration Study for Deep Foundations in Ephemeral Streams

Abstract

The duration of a flood event in an ephemeral stream is finite, ranging from a few hours to a few days. However, for design of deep foundations, an assumption is typically made by geotechnical specialists that at the time of a flood event all stream bed geomaterials are saturated and fully-buoyant. This assumption leads to larger deep foundations because full-buoyancy can significantly reduce the geomaterial resistances to applied loads. Consequently, a large increase in foundation investigation and construction costs can occur. This paper presents a case study that included an evaluation of the infiltration of transient flood waters into unsaturated geomaterials within an ephemeral stream bed. Considerable cost reductions were realized as a result of this evaluation. The presented approach permits a rational geotechnical evaluation of deep foundations in ephemeral streams.