Investigation of pile penetration in calcareous soft rock using X-ray computed tomography

Penetration of open- and closed-ended model piles into intact chalk, a soft calcareous rock, was investigated using microfocus X-ray computed tomography (XCT). Three-dimensional images the specimens showed that crushed densified chalk in their path, creating annulus around shaft, region compressed destructured below tip, fractures across cemented regions specimen. Laser-diffraction particle-size analyses after exhumation limited difference with laboratory-remoulded which suggested thorough de-cementation. Installation stresses XCT-derived densities were paired simplified cylindrical cavity expansion solution to estimate effective radial stress–void ratio states at pile tip during penetration. More complex numerical solutions could not be applied available data. This approach posed significant problems, as it suitably incorporate hardening non-linear stiffness behaviours penetration, nor account for creation discontinuities. However, estimates found converge reconstituted critical state line material high low void ratios. partially supported use framework characterise penetration proposed recent literature.