Reply to "Comment on 'Flow of wet granular materials: A numerical study' "

Area of Science:

• Physics
• Materials Science
• Granular Mechanics

Background:

• Capillary cohesion significantly enhances the quasistatic shear strength of granular materials.
• Previous work utilized a simplified approach to model this enhancement.
• The role of capillary shear stress in effective stress models was not fully accounted for.

Purpose of the Study:

• To address criticisms regarding the simplified model for capillary cohesion's effect on shear strength.
• To evaluate the accuracy and limitations of the simplified approach versus an effective stress model.
• To investigate the predictive capabilities of the effective stress assumption in various material states.

Main Methods:

• Analysis of quasistatic shear strength in granular materials.
• Comparison of a simplified cohesion model with an effective stress approach.
• Evaluation of model performance across different material states, particularly cohesion-dominated ones.

Main Results:

• The simplified approach provides a convenient estimate of Mohr-Coulomb cohesion, related to coordination number, but can err by ~25% in shear strength.
• An effective stress approach, incorporating capillary shear stress, offers quantitatively correct predictions of yield stress.
• The effective stress assumption, while successful in certain states, is predicted to fail in strongly cohesion-dominated scenarios.

Conclusions:

• While the simplified model offers a useful approximation for cohesion, its accuracy in predicting shear strength is limited.
• The effective stress model provides a more accurate prediction of yield stress by accounting for capillary shear stress.
• Further research is needed to refine models for strongly cohesive granular materials where the effective stress assumption may break down.