Special thanks go to Koos Swart of the Netherlands Institute of Ecology (NIOO-KNAW) for drilling soil cores from the IJsselmeer lake bottom for use in spore bank analyses.
To simplify the modeling process, the drill-soil interaction model is developed in the critical state.
The analytical model of drill-soil interaction was developed using the screw conveyance theory and soil shear rupture principle.
In addition, in a significant number of previous works, the drill-soil interaction was simply divided into screw conveyance and soil cutting processes.
The boundary conditions and soil mechanical property differences between these two processes were ignored in previous modeling of the drill-soil interaction.
Conventionally, modeling of drill-soil interaction was divided into soil cutting and screw conveyance processes, ignoring the differences in soil mechanical properties between them.
To explain this conveyance behavior, this section will analyze the screw conveying process, which is the foundation of the drill-soil interaction modeling.
The finite element method (FEM) and discrete element method (DEM) have been used to develop the model of drill-soil interaction [9, 10, 11, 12].
In this study, according to the structure of the drill tool, the drill-soil interaction is divided into four parts: cuttings conveyance, chip extruding, chip bulldozing, and in situ simulant cutting.
To improve the modeling accuracy, a hypothesis that divides the drill-soil interaction into four parts: cuttings screw conveyance, cuttings extruding, cuttings bulldozing, and in situ simulant cutting, is proposed to establish a novel model based on the passive earth pressure theory.
Remarkably, our investigation clearly demonstrated that the concentration of Pb in drilling fueled soil collected at the exact drilling site was greater than the safe permissible limits.
