Development and application of a binary medium bond contact model for calcareous sands

Area of Science:

• Geotechnical Engineering
• Materials Science
• Computational Mechanics

Background:

• Calcareous sand is vital for South China Sea island and reef construction.
• Understanding calcareous sand's mechanical properties is essential for engineering stability.
• Progressive failure of intergranular cementation significantly impacts macroscopic mechanical behavior.

Purpose of the Study:

• To develop a numerical model simulating the progressive failure of calcareous sand.
• To investigate the effects of bonding deterioration on mechanical properties.
• To analyze calcareous sand behavior under various confining pressures using discrete element simulations.

Main Methods:

• Development of a binary media bonding contact model.
• Implementation of a discrete element subroutine (DLL) in PFC2D (particle flow program).
• Validation through single contact compression/shear tests and biaxial shear simulations.

Main Results:

• The model accurately predicts stress-strain curves and shear strength, aligning with experimental data.
• Biaxial shear simulations under varying confining pressures demonstrate model validity.
• Analysis of damage parameters reveals their impact on mechanical behavior and microstructural evolution.

Conclusions:

• The binary media bonding contact model effectively captures the mechanical properties of calcareous sand.
• The study provides insights into macro- and micromechanical behaviors, including coordination number, fabric anisotropy, and force chain evolution.
• Findings support improved design and stability assessments for marine engineering projects utilizing calcareous sand.