Search for: All records

Abstract Soil penetration is an energy-intensive process that is common in both nature and civil infrastructure applications. Many human construction activities involve soil penetration that is typically accomplished through impact-driving, pushing against a reaction mass, excavating, or vibrating using large equipment. This paper presents a numerical investigation into the self-penetration process of a probe that uses an ‘anchor–tip’ burrowing strategy with the goal of extending the mechanics-based understanding of burrower–soil interactions at the physical dimensions and stress levels relevant for civil infrastructure applications. Self-penetration is defined here as the ability of a probe to generate enough anchorage forces to overcome the soil penetration resistance and advance the probe tip to greater depths. 3D Discrete element modeling simulations are employed to understand the self-penetration process of an idealized probe in noncohesive soil along with the interactions between the probe’s anchor and tip. The results indicate that self-penetration conditions improve with simulated soil depth, and favorable probe configurations for self-penetration include shorter anchor–tip distances, anchors with greater length and expansion magnitudes, and anchors with a greater friction coefficient. The results shed light on the scaling of burrowing forces across a range of soil depths relevant to civil infrastructure applications and provide design guidance for future self-penetrating probes. 

The effect of soil interlayering on the measured cone penetration resistance was examined in a layered soil model tested on a 9-m radius centrifuge. The soil profile consisted of a layer of sand between overlying and underlying layers of low plasticity clayey silt. The sand layer thickness varied from 0 to 240 mm (model scale) along the length of the model. The sand was loose with a relative density of 44% on one side of the model, and dense with a relative density of 88% on the other side. The clayey silt had a plasticity index (PI) of 6 and over-consolidation ratio (OCR) of about 1.5. Multiple cone penetration soundings were performed along the width and length of the model using cone penetrometers with diameters of 4, 6 and 10 mm. The model construction procedure, data processing, and cone penetration testing results are described.