TY - JOUR
T1 - Utilizing concrete pillars as an environmental mining practice in underground mines
AU - Cao, Shuai
AU - Xue, Gaili
AU - Yilmaz, Erol
AU - Yin, Zhenyu
AU - Yang, Fudou
N1 - Funding Information:
This work was financially supported by the National Natural Science Foundation of China (grant numbers: 51804017 and 51974012 ), the Open Fund of State Key Laboratory of Nonlinear Mechanics (grant number: LNM202009 ) and Fundamental Research Funds for the Central Universities (Grant No. FRF-TP-20-001A2 and FRF-BD-19-005A ).
Funding Information:
The above scientific works offer substantial information and technical data for better understanding of the strength characteristics of concrete and FRC. However, no research has been so far conducted on the laboratory and in-situ assessment of concrete pillars used as a support tool for quite a range of under different conditions such as sill pillar recovery, reduction of large stope spans and support of large size wedges. An in-depth understanding of the internal crack mechanism (through sliced images acquired from X-ray CT) and failure modes of FRC containing different fiber types and rates is critical for assessing their mechanical strength performance. This study presents the results of laboratory and field investigations of FRC to be used in the preliminary ground support design specifications of mines. A case study is also presented to better evaluate the in-situ behavior of FRC mass as a pillar, exhibiting structural behavior and integrity of FRC, which is related to rigidity, stiffness and strength. Additionally, the cavity monitoring system (CMS) scanning system was used for scanning the actual 3D shape of the mined-out areas and orebody pillars. The 3D geological software was then used for numerical modeling. After this process, the geological model was introduced into the numerical simulation software to quantitatively assess the stability of pillars before and after mining. The Voronoi diagram was used to calculate the safety factors of pillars. The main goals of this study are: i) to assess the feasibility of FRC as a major ground support in underground mines; ii) to broadly analyze its internal structure by 3D reconstruction technology; iii) to assess the relationship between compressive strength and internal structure of FRC; iv) to understand the failure modes and structural characteristics of FRC;, and v) to carry out on-site pillar mining application to assess its applicability in real underground conditions.This work was financially supported by the National Natural Science Foundation of China (grant numbers: 51804017 and 51974012), the Open Fund of State Key Laboratory of Nonlinear Mechanics (grant number: LNM202009) and Fundamental Research Funds for the Central Universities (Grant No. FRF-TP-20-001A2 and FRF-BD-19-005A).
Publisher Copyright:
© 2020 Elsevier Ltd
Copyright:
Copyright 2020 Elsevier B.V., All rights reserved.
PY - 2021/1/1
Y1 - 2021/1/1
N2 - Ground control is an integral element of mine design and worker safety. The use of concrete pillars for underground mines is of paramount importance to maintaining the economic and operational security of structures. This paper deals with the use of fiber-reinforced concrete (FRC) as pillars via laboratory and field tests. The strength performance of prepared concrete reinforced with glass, polypropylene and polyacrylonitrile fibers was researched by a mechanical press and a computed tomography (CT) tool. Samples were tested for fiber volume fractions of 0, 0.4, 0.8 and 1.2 wt%, respectively. Results have indicated that, with the addition of fibers, the strength was improved first due to a bridging effect and then decreased due to a pull-out effect. Compared to the reference sample, the absorbed energy prevents FRC from deterioration by mechanisms of matrix cracking, fiber-matrix interface debonding and fiber rupture. The peak strains of FRC linearly rise with increasing fiber. The gray value distribution curves have also good correspondence with 2D CT pore and crack distributions, which reveal that gray value processing could depict the structural behavior of concretes reinforced with or without fiber. Theoretical analyses show that the pillar remains stable for sustainable mining. Besides, the location and size of FRC pillars are suitable for numerical calculations of the trial stope. The findings of this study can offer a key reference for the orebody pillar recovery in underground mines.
AB - Ground control is an integral element of mine design and worker safety. The use of concrete pillars for underground mines is of paramount importance to maintaining the economic and operational security of structures. This paper deals with the use of fiber-reinforced concrete (FRC) as pillars via laboratory and field tests. The strength performance of prepared concrete reinforced with glass, polypropylene and polyacrylonitrile fibers was researched by a mechanical press and a computed tomography (CT) tool. Samples were tested for fiber volume fractions of 0, 0.4, 0.8 and 1.2 wt%, respectively. Results have indicated that, with the addition of fibers, the strength was improved first due to a bridging effect and then decreased due to a pull-out effect. Compared to the reference sample, the absorbed energy prevents FRC from deterioration by mechanisms of matrix cracking, fiber-matrix interface debonding and fiber rupture. The peak strains of FRC linearly rise with increasing fiber. The gray value distribution curves have also good correspondence with 2D CT pore and crack distributions, which reveal that gray value processing could depict the structural behavior of concretes reinforced with or without fiber. Theoretical analyses show that the pillar remains stable for sustainable mining. Besides, the location and size of FRC pillars are suitable for numerical calculations of the trial stope. The findings of this study can offer a key reference for the orebody pillar recovery in underground mines.
KW - Compressive strength
KW - Computed tomography
KW - Environmental mining practice
KW - Fiber reinforced concrete
KW - Numerical simulation
KW - Ore pillar recovery
UR - http://www.scopus.com/inward/record.url?scp=85089508193&partnerID=8YFLogxK
U2 - 10.1016/j.jclepro.2020.123433
DO - 10.1016/j.jclepro.2020.123433
M3 - Journal article
AN - SCOPUS:85089508193
SN - 0959-6526
VL - 278
JO - Journal of Cleaner Production
JF - Journal of Cleaner Production
M1 - 123433
ER -
