Physical modeling in calibration chamber of the evolution of the soil stiffness around a piezocone probe under cyclic axial loading in saturated clay

Abstract. Cone Loading Test (CLT) is a new in-situ geotechnical soil test, considered as an improvement of the piezocone penetration test (CPTu). The principle is to carry out a conventional static penetration test with a piezocone up to a given depth, then static and/or cyclic loadings are performed. The interpretation of the CLT at this depth allows a better soil characterization by providing the stiffness parameters as well as the strength parameters, which are complementary of those obtained during the conventional static penetration test. The aim of this paper is to present the results of physical modeling of cyclic CLT tests carried out in the calibration chamber of the Navier Laboratory at the Ecole Nationale des Ponts & Chaussées, France. A piezocone probe of 36 mm in diameter is jacked into saturated Kaolinite clay and subjected to cyclic axial loading up to a very large number of cycles (105 cycles). The evolution of skin friction and tip stiffness at the soil-pile interface during cyclic loading is studied. A parametric study is conducted to examine the influence of number of cycles as well as stress level on the measured parameters.