An Efficient Damage-Plasticity DEM Contact Model for Highly Porous Rocks

Area of Science:

• Computational Geomechanics
• Material Science
• Numerical Modeling

Background:

• Accurate simulation of porous soft rock behavior is essential for geotechnical engineering, particularly in pile penetration problems.
• Existing models often struggle to capture the complex micro-scale mechanisms governing the macroscopic response of these materials.
• The need for efficient and scalable numerical methods is critical for simulating large-scale geotechnical scenarios.

Purpose of the Study:

• To develop and validate a novel discrete element method (DEM) model for simulating porous soft rock behavior.
• To incorporate micro-scale damage and plastic deformation within a macro-element framework for enhanced realism.
• To assess the model's efficiency, scalability, and predictive capability for pile penetration scenarios.

Main Methods:

• A new discrete element method (DEM) model was developed, utilizing macro-element theory and damage laws for micro-scale plastic deformations.
• A far-field interaction framework was employed to handle high porosity, irregular grains, and bond fragments, allowing non-overlapping particles to transmit forces.
• A coupled DEM-Finite Differential Method (FDM) framework was used to enhance the efficiency of 3D numerical simulations.

Main Results:

• The model was calibrated and successfully replicated the behavior of Maastricht calcarenite, exploring its mechanical response within the critical state theory framework.
• Simulations of cone-ended penetration tests showed a good fit between experimental and numerical results, validating the model's predictive power.
• The coupled DEM-FDM approach demonstrated significant efficiency gains for 3D simulations.

Conclusions:

• The proposed DEM model effectively reproduces the behavior of porous soft rocks, including complex micro-scale phenomena.
• The model's efficiency and scalability make it suitable for simulating large-scale geotechnical problems like pile penetration.
• This novel approach provides insights into the microscopic mechanisms controlling the macroscopic response in soft-rock/structure interaction.