Evaluating hydraulic parameters in clays based on in situ tests

Abstract

The permeability of soil is an important factor controlling the flow of water through the subsoil. The article presents the results of studies of hydraulic parameters for overconsolidated clays using in situ tests. Using the excess pore pressure normalization technique, both in the case of monotonic and dilatory dissipation tests, and the time at which 50% dissipation of excess pore water pressure takes place, as well as taking into account the rigidity index of the analyzed soil, it was possible to estimate the permeability and consolidation coefficients for the analyzed clays. Based on these studies, simple relationships between the permeability coefficient and the soil behavior-type index are proposed. Proposed formulas may be applied for overconsolidated cohesive soils with soil behavior-type index values within the range of 2.05–3.30 and described in Robertson’s chart as overconsolidated silty clays, clays and heavily overconsolidated and cemented fine-grained soils. Although our proposal of determining flow parameters has been calibrated only for two analyzed cases, its utility for wider use in other overconsolidated fine-grained soils may also be taken into account.

Keywords

• permeability
• dissipation test
• soil behavior type index
• cohesive soils
• 74l10
• 86a60