Hybrid Failure of Cemented Paste Backfill

Andrew Pan,Mohammadamin Jafari,Murray Grabinsky,Lijie Guo

doi:10.3390/min11101141

Andrew Pan, Mohammadamin Jafari + Show 2 more

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https://doi.org/10.3390/min11101141

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Abstract

The hybrid failure is a coupled failure mechanism under the action of tensile and shear stresses. The failure is critical in cemented paste backfill (CPB) since there are no visible signs prior to the failure. Few studies have been conducted on the coupled stress response of CPB. This is most likely due to a lack of suitable laboratory equipment and test procedures. This paper presents a new punching shear apparatus to evaluate the hybrid failure of CPB. We harness two-dimensional finite element analysis (FEA) for supplementing experimental study in providing stress transformation, deformation, and possible failure mechanisms. Our study suggests that the coupled stress is a combination of tensile and shear strength in function of the angle of the frustum. The strengths measured by the coupled stress are comparable to those measured by direct shear and tensile strength tests, in which the strength properties of CPB are curing time and binder content dependent. The FEA results substantiate the effectiveness of proposed model for predicting the hybrid failure of CPB.

Highlights

We developed a new punching shear apparatus to evaluate the shear and tensile behavior of cemented paste backfill (CPB) in this study
We focused on the applications and a closer examination of the hybrid failure through both laboratory fracture morphology and numerical simulation
We observed that fracture morphology is strongly related to the angle of the frustum, which is consistent with the numerical simulation

Summary

Introduction

The geomechanical properties of cemented paste backfill (CPB) and its design have been the interest of industrial groups and academic communities. CPB plays an increasingly important role in many modern mines throughout the world, in Canada and Australia. CPB is a composite backfill technique used as regional ground support. It is a homogenous mixture obtained from mixing tailings with water and hydraulic binder. The designs of CPB are based on regional ground conditions, tailing behaviors, and operational requirements [1,2]. CPB consists of 70% to 85% fine particles by weight and incorporates 2% to 9% binder of Normal Portland Cement (NPC) and possibly fly ash or ground blast furnace slag [3]

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