Experimental study on the mechanical characteristics of weakly cemented mudstone under different loading rates

Area of Science:

• Geotechnical Engineering
• Rock Mechanics
• Mining Engineering

Background:

• Floor heave in weakly cemented mudstone roadways is a significant safety and efficiency concern in China's western coal mining regions.
• Varying mining rates induce fluctuating support stresses, exacerbating floor heave issues.

Purpose of the Study:

• To investigate the mechanical properties of weakly cemented mudstone under different loading rates.
• To understand the influence of loading rate on strength, deformation, damage, and failure characteristics.
• To provide a theoretical basis for mitigating floor heave in deep roadways.

Main Methods:

• Conducted uniaxial mechanical tests on weakly cemented mudstone specimens.
• Utilized acoustic emission monitoring concurrently with mechanical testing.
• Tested specimens at various loading rates: 0.005, 0.01, 0.05, and 0.1 mm/s.

Main Results:

• Peak strength and elastic modulus increased significantly with loading rate; peak axial strain and radial deformation decreased.
• A power-law relationship was observed between expansion strain and loading rate.
• Acoustic emission activity and damage variables increased with loading rate.
• Failure mode shifted from progressive to sudden, and from shear to tensile-shear composite failure.

Conclusions:

• Loading rate significantly influences the mechanical behavior and failure mechanisms of weakly cemented mudstone.
• Findings offer a theoretical foundation for understanding and controlling floor heave in deep coal mine roadways.