Interrelationship between Undrained Shear Strength from DMT and CPTU Tests for Soils of Different Origin

Abstract

Abstract The article presents test results on the use of the flat dilatometer test (DMT) to evaluate changes in undrained shear strength su in soils of various origins. Reference values for the undrained shear strength calculated with Marchetti’s original formula were su values obtained from the piezocone penetration tests. The tests were conducted at eight investigation sites in Poland, where five groups of soils were separated: loess-deluvial, loess-deluvial cemented, young till, aged till, and Pliocene clay. The soils exhibited varied overconsolidation effects. The study results revealed that the factors influencing the relationship between undrained shear strength and the KD coefficient from DMT test were various because of the origin, grain size distribution of the soils and cementation. In order to include the influence of overconsolidation and grain size distribution in calibration of su from DMT, a modified KD1 coefficient was introduced into the formula describing this relationship. The final solution was obtained with multiple linear regression. A relatively high statistical evaluation of this relationship was determined for aged till and deluvial and uncemented loess.