Characterization of Structural Profiles in Clay‐Rich Marsh Soils by Cone Resistance and Resistivity Measurements

Abstract

The management of clay‐rich soils in agriculture is mainly dependent on their hydromechanical properties that govern their structural evolutions. These structural evolutions are commonly described along the shrinkage curves obtained in a laboratory. Nevertheless, the field survey needs tools of in situ investigations able to characterize the structural profile evolutions of soils through the seasons. This paper presents a method based on the cone penetration and resistivity measurement by penetrometer–salinometer coupling that was gauged in the West Marsh of the French Atlantic Coast. First, the parallel measurements of water and cone resistance (Qd ) profiles in clay dominant soils, characterized by very large ranges of water content (W), allows the calculation of a Perdock's‐type equation that links the Qd profiles and the shrinkage curve of the clay dominant material. Second, thanks to the homogeneity of mineralogy and cationic exchange capacity of the soil, the structure–resistivity relationship was gauged according to the Archie's law taking into account porosity (ϕ), saturation index of the soil (Sat), and the resistivity of the wetting fluid (ρw). The vertical evolutions of structure, resistivity, and cone resistance can be represented in a crossed diagram showing the shrinkage curve–resistivity and Qd profile relationships. Finally, the structural profiles of soils can be modeled from the recorded resistivity and Qd profiles taking into account the ρw