Strength deterioration and energy dissipation characteristics of cemented backfill with different gangue particle size distributions

Abstract

The particle size distribution of gangue is an important factor affecting the strength of backfill body. To uncover the strength deterioration law and energy dissipation characteristics of cemented backfill with different gangue particle sizes, the uniaxial compressive strength mechanical tests were carried out by scanning electron microscopy analysis combined with rock mechanics test system and acoustic emission monitoring equipment. The deformation failure mode, mechanical characteristics, acoustic emission response characteristics and energy dissipation characteristics of backfill samples with different particle size distribution under uniaxial compression were studied. The results shown that: The particle size distribution of gangue material is very important to the performance of backfill body. The compressive strength of the backfill sample with medium particle size was the largest. As the particle size of the gangue increases, the acoustic emission response degree of the backfill firstly increases followed by a subsequent decrease. The acoustic emission ringing count and energy rate reach the peak when the backfill was destroyed. Building upon the principle of energy dissipation and release, the defined energy dissipation ratio was used as the strength deterioration index of the backfill body. The energy dissipation ratio of fine grain size, medium grain size and coarse grain size filling was 19.64%, 7.85% and 12.93%, respectively. When the failure mode of the backfill shifts from tensile failure to shear failure, the energy dissipation ratio decreases from 19.64% to 7.85%. The storage capacity of elastic strain energy in the backfill gradually increases, and the strength degradation degree of backfill gradually decreases.

Keywords

• Cemented gangue backfill body
• Mechanical properties
• Strength deterioration
• Acoustic emission
• Energy dissipation ratio