A Discrete Element Modeling Study on CPT Penetration of Calcareous Sand Considering Dual Porosity Structure

This paper introduces a discrete element numerical simulation method for calcareous sand particles that incorporates dual porosity structures. The method focuses on three key characteristics of calcareous sand in comparison to quartz sand: abundant dual porosity structure, pronounced particle aspect ratio, and susceptibility to breakage. The study involves CPT penetration simulations to analyze the effects on cone tip resistance, side friction, force chain transmission, and displacement fields during penetration. The findings indicate that internal porosity is the primary factor influencing the overall strength of the particles, while external porosity significantly affects the contact strength between particles. As the internal and external porosity of calcareous sand increases, the maximum values of cone tip resistance and side friction during CPT penetration decrease accordingly. Simultaneously, the stable region of the penetration curve expands, and the evolution of force chains and displacement fields is suppressed. Moreover, the aspect ratio of particle shape has a significant impact on the packing behavior of calcareous sand and also influences CPT penetration outcomes. The susceptibility of calcareous sand particles to breakage is a notable characteristic, with internal porosity playing a crucial role in particle breakage. The proposed model offers valuable insights for in-situ testing of calcareous sand.