Evaluation of coefficient of permeability of saturated soils based on CPTU dislocation theory

The parameters obtained from measurements during piezocone penetration tests (CPTU) are commonly used for soil profiling and geostratigraphy as well as the assessment of geotechnical design. Since a dissipation test often takes significant time, efforts have been made to continuously evaluate the coefficient of permeability of saturated soils using the measured cone tip resistance, sleeve fiction and pore water pressure. In this study, the researches on evaluation of the coefficient of permeability of saturated soils are briefly reviewed and analyzed. Two novel methods based on the dislocation theory and the cylindrical flow model to estimate in-situ horizontal permeability are suggested. Piezocone penetration tests are conducted at typical sites. Horizontal permeability tests in laboratory on undisturbed samples of cohesive soils from high-quality thin-wall samplers and field pumping tests in borehole on cohesionless soils are also performed. A total of five methods are used to estimate the coefficient of permeability of soils, and the results are compared with those from laboratory and field tests. It is concluded that the values of coefficient of permeability evaluated from the proposed methods are more representative of the laboratory and field values than those evaluated using the available alternative methods. The dislocation theory can be used to estimate the coefficient of permeability of soils, but the accuracy depends on the flow model in porous media. For a standard cone with pore pressure element located at the shoulder of cone penetrometer (u₂ position), the radial flow normal to a cylindrical surface can support the best prediction of in-situ permeability.