A New Method for the Estimation of Hydraulic Permeability, Coefficient of Consolidation, and Soil Fraction Based on the Dilatometer Tests (DMT)

The main issue of the paper is the estimation of soil hydraulic permeability based on the DMT test. DMTA, DMTC and SASK methods performed in the Nielisz dam, Stegny and the SGGW Campus of the Warsaw University of Life Sciences sites are described. The article presents the implementation of the dilatometer Marchetti test (DMT) in the determination of soil fraction and effects of its occurrence in the subsoil, tested in the Nielisz dam located in the Wieprz river valley in the Lublin province, and in various sites in Warsaw (Stegny site and SGGW Campus of the Warsaw University of Life Sciences). In order to acquire the needed data, the flat dilatometer test (DMT) method was used. A direct and indirect pressure methodology of interpreting soil swelling was characterized in the article. The paper shows the possibilities of determining sand, silt and clay soil fractions based on po and p1 pressures from dilatometer tests (DMT) and the effective (σ’vo) and total (σvo) vertical in situ overburden stress. Additionally, the main advantage of this paper is the proposal of use of a new chart to determine hydraulic permeability and soil fraction, based on DMT tests.

Effects of test procedure on flat dilatometer test (DMT) results in intermediate soils

The evaluation of rate effects on the flat dilatometer test (DMT) can best be developed with some knowledge of the excess pore pressures generated during penetration, dissipation, and subsequent membrane expansion. While research that includes pore pressure measurements in the DMT has documented drainage conditions in clean sand and soft clay, further studies are required to determine the drainage conditions during the DMT in intermediate permeability soils, such as silts. For that purpose, a simple and inexpensive research device has been developed for monitoring pore pressures at the center of the DMT blade. Data using both a standard DMT and the modified research DMT from various tests in sand, silt, and clay have been compared in a space that correlates dimensionless velocity to degree of drainage. In this space, it is possible to evaluate whether partial drainage is taking place. Measurements indicate that the DMT is essentially undrained in soft clay and dominated by penetration pore pressures, is drained in clean sand and is partially drained in intermediate permeability soils, such as silt. A method is suggested to identify soils where partial drainage may influence the standard DMT results.