Macro and micro analysis on coal-bearing soil slopes instability based on CFD-DEM coupling method

Area of Science:

• Geotechnical Engineering
• Computational Mechanics
• Environmental Science

Background:

• Coal-bearing soil slopes are susceptible to instability and failure, particularly during rainfall events.
• Understanding the micromechanisms of slope failure is crucial for effective design and protection.
• Existing models often lack the micro-scale detail to fully capture fluid-solid interactions in soil slopes.

Purpose of the Study:

• To develop and validate a three-dimensional computational model for analyzing coal-bearing soil slope instability during rainfall.
• To investigate the micromechanisms of failure, including fluid-solid coupling effects.
• To explore the relationship between microscopic particle behavior and macroscopic slope mechanics.

Main Methods:

• Combined computational fluid dynamics (CFD) and discrete element method (DEM) to create a fluid-solid coupling model.
• Simulated rainfall infiltration and its effects on soil particle interactions.
• Validated the numerical model against outdoor experimental data from rain-washed slopes.

Main Results:

• The primary failure mode identified was rainwater washing, leading to an approximately linear sliding surface.
• Rainfall significantly altered microscopic soil parameters, including force chains, coordination number, and porosity.
• Particle porosity at the slope's top increased from 0.35 to 0.80 in the unstable state, directly correlating with macroscopic mechanics.

Conclusions:

• The CFD-DEM model effectively simulates the micromechanisms of instability and failure in coal-bearing soil slopes under rainfall.
• Microscopic changes in particle parameters, such as increased porosity, are key drivers of macroscopic slope failure.
• This research provides a theoretical foundation for slope protection and offers a micro-macro perspective for geotechnical analysis.