Investigations of Pile-Soil Interaction in Cohesive Soils-Paper

Paper

Pdf Summary

The study examines pile–soil interaction and plug formation in open-ended piles installed in cohesive soils, an area less developed than research on granular soils. Because soil–steel friction and stress development affect pile installation resistance and load capacity, the authors review existing theory and present a preliminary laboratory method for measuring interface friction.<br /><br />The apparatus applies controlled vertical stress to water-prepared soil samples and measures the torsional moment needed to rotate a smooth steel plate against the soil. Tests used Bolus kaolin clay and sand. For kaolin, torsional resistance generally increased as consolidation reduced water content. The measured relationship between shear and normal stress gave approximate surface-friction slopes of 0.36 for kaolin and 0.20 for sand. These results broadly align with prior research, though interpretation is limited by incomplete characterization of the soils and assumptions about their internal friction angles.<br /><br />The findings suggest that interface friction depends on soil type, consolidation, and water-related properties. Such friction influences shear and radial stresses within piles and therefore the likelihood of plug formation. The simple test method appears workable, but further development and validation are needed. The authors plan to build an automated apparatus capable of measuring moments, stresses, and displacements, enabling more detailed investigation of soil properties and pile–soil interaction.

Keywords

open-ended piles

pile-soil interaction

plug formation

cohesive soils

soil-steel friction

interface friction

torsional moment

Bolus kaolin clay

consolidation

load capacity