A new loading-unloading experimental method for simulating the change of mining-induced stress

Area of Science:

• Geotechnical Engineering
• Rock Mechanics
• Material Science

Background:

• Understanding sandstone behavior under cyclic loading is crucial for infrastructure stability.
• Existing experimental methods can be limited by sample variability.

Purpose of the Study:

• To propose and validate a new triaxial loading-unloading experimental method to mitigate sample variations.
• To investigate the influence of initial hydrostatic stress and loading-unloading rates on sandstone strength and failure mechanisms.

Main Methods:

• Development of a novel triaxial seepage device.
• Implementation of an alternating loading-unloading experimental technique.
• Analysis of stress-strain curves and failure modes under varying hydrostatic stress and loading rates.

Main Results:

• Sandstone strength and axial strain at failure increase with initial hydrostatic stress.
• Strength decreases with higher loading-unloading rates.
• Failure modes transition from tensile to shear-dominated with increasing hydrostatic stress.
• Stress-strain curves exhibit wave-like patterns, with volatility influenced by stress and loading rate.

Conclusions:

• The proposed method effectively reduces sample variations in triaxial seepage tests.
• Initial hydrostatic stress is a key factor in enhancing sandstone strength and controlling failure modes.
• Loading-unloading rates critically influence rock strength and the progression of failure mechanisms.