Determination of hydraulic conductivity using HPT & CPTu

In geotechnical engineering insitu tests are becoming increasingly popular to determine the hydraulic conductivity of soils. Direct push methods such as piezocone penetration test CPTu or the hydraulic profiling tool HPT allow characterizations along a linear profile. The determination of hydraulic conductivity with HPT is an alternative to CPTu for drained and partially drained conditions. Thereby, water is continuously injected from a small screened port at the probe into the soil. Based on the required pressure to inject the water into the soil and the constant flow rate, the hydraulic permeability can be determined for a certain range of drainage conditions. The present article compares HPT and CPTu results with slug tests, executed at different test sites in a wide range of grain size distributions. Based on this comparison, a new correlation was elaborated for HPT which enables an improved characterization of hydraulic conductivity.