Numerical simulation of micro crack evolution and failure modes of limestone under uniaxial multi-level cyclic...

Area of Science:

• Geotechnical Engineering
• Rock Mechanics
• Materials Science

Background:

• Deep rock structures face complex cyclic disturbances from seismic events and blasting.
• Understanding rock mechanical response under multi-level cyclic loading is crucial but insufficient.
• Cyclic loading effects on rock strength and fracture behavior require detailed investigation.

Purpose of the Study:

• To investigate the mechanical response and fracture behavior of limestone under multi-level cyclic loading.
• To analyze the influence of loading amplitude and cycle times on rock properties.
• To validate numerical simulation results against experimental data.

Main Methods:

• Performed multi-level cyclic loading experiments on limestone specimens.
• Utilized Particle Flow Code 2D (PFC^2D) to establish a Discrete Element Method (DEM) model.
• Compared simulation outcomes with experimental stress-strain data and fracture patterns.

Main Results:

• Low cycle loading initially strengthens rock, while high cycle loading causes deterioration.
• Increased loading amplitude accelerates initial crack formation.
• Higher cycle counts per level induce more microcracks.
• Tensile cracks concentrate at specimen edges, while shear cracks dominate the center.
• Mixed shear and tensile failure modes become prevalent with increasing amplitude.

Conclusions:

• Rock behavior under cyclic loading is dependent on cycle number and amplitude.
• DEM simulations in PFC^2D accurately replicate experimental rock mechanics.
• Findings provide insights into deep rock mass stability under dynamic disturbances.