Flexural Behavior of Fiber Reinforced Cemented Tailings Backfill Under Three-Point Bending

Shuai Cao,Erol Yilmaz,Gaili Xue

doi:10.1109/access.2019.2943479

Abstract

Mining methods use cemented tailings backfill (CTB) for filling mined-out voids and make operations safer since employees are working under it. Hence, the durability behavior of CTB is of great importance in applications, for example, in the assessment of slope stability when extracting ore left in neighboring stopes. Addition of cement content would increase the strength of CTB but creates extra costs to mines. To cut cement-related costs as well as improve durability, different types of fibers are added to CTB samples. This paper aims to analyze flexural behavior of fiber reinforced CTB samples under three-point bending loading. To do so, a comprehensive laboratory work was undertaken to explore the effect of fiber reinforcement on bending resistance of CTB samples, based on orthogonal experimental design. The effect of fiber type (FT), fiber content (FC), solid content (SC) and cement-to-tailings ratio (c/t) on bending characteristics was investigated. Results indicate that the addition of fiber enhances the bending strength of fiber reinforced CTB samples and the bearing capacity after the peak in the load-deflection curve. Fibers help correct the faintness of CTB samples by mobilizing tensile strength along the failure planes. The crack resistance of fiber is reflected in the crack propagation stage. Secondly, the order of the sensitivity of four factors on bending strength of fiber reinforced CTB samples is as follows: c/t > SC > FT > FC. Lastly, the main findings of this study can provide a major reference for CTB’s last design in underground mining.

Highlights

Underground mining is one of the main ways to obtain metal and non-metallic mineral resources
Can the fiber material be ‘‘cracked rather than broken’’ under the bending loading? Can we explore the preparation of fiber reinforced cemented tailings backfill (CTB) with low cost, high overall strength, good flexural and crack resistance, which can reduce the secondary dilution caused by the backfilling of CTB mass into mined-out stope, and can realize safe and efficient recovery? This study clarifies these issues
If fibers in the most dangerous surface of CTB are unplugged, they are the end of fiber action

Summary

Introduction

Underground mining is one of the main ways to obtain metal and non-metallic mineral resources. There are numerous underground mining methods with and without backfilling, considering the ore being mined and the nature of the orebody [4]–[6]. For underground mining of metal mines, mining method with the backfill has been commonly used due to its high recovery rate, reliable safety and reduced the surface tailings storage requirement [15]–[18]. Compared with sublevel stoping and shrinkage, cut and fill mining offer the advantage of full selectivity and is preferred in situations where orebody dips steeply [28], [29]. In this technique, the voids created by mining is backfilled with an engineered mix of tailings

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