Content and gradation of aggregates effect on compaction property of gangue backfill and strata movement: experiments and models

It is of great significance to study compaction characteristics of gangue backfill for recycling mining waste, solving environmental problems and controlling surface subsidence. Gangue aggregate accounts for more than 70% of filling materials, and the content and gradation of aggregates are the decisive factors affecting the compaction characteristics of gangue backfill. This paper investigates the effects of content and gradation of aggregates on stress-strain behavior, compression modulus and porosity of gangue backfill based on the uniaxial compression experiment, and the gradation of aggregate obeyed the Talbot gradation theory. The constitutive model of gangue backfill considering content and gradation of aggregates was constructed and embedded in the numerical model. The influences of the content and gradation of aggregates on the advance support pressure and roof subsidence were analyzed by numerical simulation. The results show that the relations between the strain increment, compression modulus and porosity of gangue backfill and the aggregate gradation can be characterized by a quadratic polynomial. The advance support pressure and roof subsidence firstly decrease and then increase with the increase of aggregate gradation. There is a positive correlation between the advance support pressure, roof subsidence and the aggregate content. When the Talbot index of aggregate gradation is 0.4 and the aggregate content is 70%, the effect of reducing subsidence is superior.

Automated summary

This paper investigates the compaction characteristics of gangue backfill and finds that the content and gradation of aggregates are important factors affecting the compaction characteristics. A constitutive model considering the content and gradation of aggregates is constructed and embedded in the numerical model. The results show that the stress-strain behavior, compression modulus, and porosity of gangue backfill can be characterized by the gradation of aggregates. Additionally, the advance support pressure and roof subsidence are influenced by the aggregate gradation and content.