A Narrow Wall System to Capture Temperature-Stress-Strain Behavior in Paste Backfill

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A Narrow Wall System to Capture Temperature-Stress- Strain Behavior in Paste Backfill

Journal: Geotechnical Testing Journal Manuscript ID GTJ-2017-0383

Manuscript Type: Technical Manuscript Date Submitted by the Author: 25-Oct-2017

Complete List of Authors: Ting, Wee Kiet; Universiti Malaysia Sarawak, Civil Engineering Hasan, Alsidqi; Universiti Malaysia Sarawak, The Department of Civil Engineering

Sahdi, Fauzan; Universiti Malaysia Sarawak

Taib, Siti Noor Linda ; Universiti Malaysia Sarawak, The Department of Civil Engineering

Sutan, Norsuzailina; Universiti Malaysia Sarawak

bin Abdul Aziz, Badhrulhisham ; Universiti Malaysia Pahang Faculty of Chemical and Natural Resources Engineering

Fourie, Andy; University of Western Australia, Civil, Environmental and Mining Engineering

ASTM Committees and Subcommittees:

D18.06 Physical-Chemical Interactions of Soil and Rock < D18 Committee on Soil and Rock

Keywords: Paste backfill, Narrow wall, Stress Strain Behavior, Temperature, Arching

Abstract:

Placing mine tailings back underground, into mined-out stopes, is becoming increasingly used internationally, providing as it does improve ore recovery, reduced dilution of valuable ore and environmental benefits due to reduced size of surface tailings storage facilities. In recent years a number of stopes backfilled with cemented paste backfill have been instrumented with load cells and piezometers, to improve our

understanding of in-situ behavior. Many of these studies have reported results that show increases in measured total stresses when there is no increase in applied load, i.e. even when the backfilling process is long completed. One explanation is that these stress increases result from expansive volume changes of the backfill as it hydrates and generates heat. This paper describes a laboratory apparatus developed to investigate this hypothesis, focusing on modeling narrow stopes as these are relatively common in backfill applications. Results from the experiments agree qualitatively with the reported field observations, showing clear increases in measured wall pressure during periods of temperature increase. The results are important for current and future backfill operations, as it confirms the measured stress increases are realistic and believable, and do not represent a malfunction of the instrumentation, as has previously been speculated.

https://mc04.manuscriptcentral.com/astm-gtj Geotechnical Testing Journal

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A Narrow Wall System to Capture Temperature-Stress-Strain

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Behavior in Paste Backfill

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Authors:

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Ting Wee Kiet¹, email: [email protected] 5

Alsidqi Hasan*¹, email: [email protected] 6

Fauzan Sahdi¹, email: [email protected] 7

Siti Noor Linda Taib¹, email: [email protected] 8

Norsuzailina Mohamed Sutan¹, email: [email protected] 9

Badhrulhisham Abdul Aziz², email: [email protected] 10

Andy Fourie³, email: [email protected] 11

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* Corresponding author, 13

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Address of authors:

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1The Department of Civil Engineering, Universiti Malaysia Sarawak, 94300 Kota Samarahan, 16

Sarawak, Malaysia 17

2Rare Earth Research Center, Universiti Malaysia Pahang, 26600 Pekan, Malaysia 18

3School of Civil, Environmental and Mining Engineering, The University of Western 19

Australia, 35 Stirling Hwy, Crawley, Perth WA 6009, Australia 20

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For Review Only

Page 2 of 24 ABSTRACT 26

Placing mine tailings back underground, into mined-out stopes, is becoming increasingly 27

used internationally, providing as it does improve ore recovery, reduced dilution of valuable 28

ore and environmental benefits due to reduced size of surface tailings storage facilities. In 29

recent years a number of stopes backfilled with cemented paste backfill have been 30

instrumented with load cells and piezometers, to improve our understanding of in-situ 31

behavior. Many of these studies have reported results that show increases in measured total 32

stresses when there is no increase in applied load, i.e. even when the backfilling process is 33

long completed. One explanation is that these stress increases result from expansive volume 34

changes of the backfill as it hydrates and generates heat. This paper describes a laboratory 35

apparatus developed to investigate this hypothesis, focusing on modeling narrow stopes as 36

these are relatively common in backfill applications. Results from the experiments agree 37

qualitatively with the reported field observations, showing clear increases in measured wall 38

pressure during periods of temperature increase. The results are important for current and 39

future backfill operations, as it confirms the measured stress increases are realistic and 40

believable, and do not represent a malfunction of the instrumentation, as has previously been 41

speculated.

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Keywords: paste backfill, narrow wall, stress strain behavior, temperature, arching 44

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INTRODUCTION 46

Stress distribution analysis of granular fill material confined within a narrow space 47

between two walls has drawn attention of Landry et al. (2004). Such analyses are not only 48

applicable to granular materials but have also been used to explain the geotechnical 49

mechanisms within paste backfill in underground mine stopes (Belem and Benzaazoua 2007).

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