Development and Testing of a Multiflow In Situ Permeameter

The horizontal permeability of thinly bedded foundation soils is one of the primary factors that controls the time-rate of consolidation during embankment construction. This paper explores using a tri-element water source housed in a push-in CPT permeameter device to measure the in situ horizontal permeability of thinly bedded sediments. As constant water pressure is applied, horizontal radial flow is achieved in the middle element because its flow is constrained by the parallel flow from the above and below elements. This effect eliminates any tendency for immediate vertical flow from the middle element and allows for direct measurement of the horizontal permeability using the flow equations derived for steady-state radial flow to a fully penetrating well. Although this paper explores the use of this concept for obtaining design properties for time-rate of consolidation calculations for low permeability soils with prefabricated vertical drains, this concept may also be utilized for any thinly bedded sediments where obtaining the true horizontal permeability of the soil is required, such as environmental and ground water assessments.