Mechanical Properties and Microstructure Evolution of Cemented Tailings Backfill Under Seepage Pressure

Yuxian Ke,Shi Wang,Kaijian Hu,Huadong Guan,Qiusong Chen,Yang Shen,Chen Qing

doi:10.3389/fmats.2021.818698

Abstract

Cemented tailing backfill (CTB) in underground mine inevitably experiences seepage field, which complicates its mechanical behavior. In this study, the mechanical properties and microstructure characteristics of CTB under different seepage water pressures (SWPs) were investigated. The results show that, with the increase in SWP, the mechanical properties of CTB decrease, but the decreasing trend reduces gradually. Higher SWP leads the microstructure of CTB looser and more porous, and the largest proportion of pores initiated and propagated by SWP is micropores, which means the damage in CTB under seepage is mostly caused by micropores. Besides, the mechanical properties of CTB under seepage decrease exponentially with the increase in porosity and present linearly inverse proportional relation to the pore area fractal dimension. Results above indicate that SWP has a significant deterioration effect on the mechanical properties and microstructure of CTB. The research could not only extend the knowledge of mechanical properties and microstructure characteristics of CTB under seepage but also provide a theoretical reference for mechanical index determination and stability analysis of CTB in water-rich underground mines.

Highlights

Cemented tailing backfilling is the most effective way to maximize the utilization of tailings and to minimize the amounts of environmental hazards (Ke et al, 2017a; Cao et al, 2018; Li et al, 2021a; Li et al, 2021b; Tana et al, 2021)
The results suggested that seepage water pressures (SWPs) had an obvious weakening effect on the uniaxial compressive strength (UCS) and elastic modulus of Cemented tailing backfill (CTB), whereas the weakening effect was decreasing overall with the increase in SWP; that is, the higher the SWP, the less apparent the weakening effect on mechanical properties of CTB
The mechanical properties of CTB are related to its internal microstructure (Yang et al, 2019; Zhou et al, 2019; Tana et al, 2021); the results indicated that the seepage would cause a certain degree of damage to the internal microstructure of CTB

Summary

Introduction

Cemented tailing backfilling is the most effective way to maximize the utilization of tailings and to minimize the amounts of environmental hazards (Ke et al, 2017a; Cao et al, 2018; Li et al, 2021a; Li et al, 2021b; Tana et al, 2021). It has become the preferred mining method for the sustainable development of underground mining industry (Fall and Samb, 2009; Ke et al, 2017b; Yu et al, 2021; Chen et al, 2022). The strength index of CTB is bound to be conservatively designed under safety first

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