Experimental and Theoretical Studies on the Creep Behavior of Bayer Red Mud

Advances in Civil Engineering, May 2018

Long-term stability and safety of the Bayer red mud (BRM) disposal field is very important for the local residents’ life, which necessitates the knowledge of its creep behavior. In order to investigate the creep behavior of BRM, a series of triaxial drained creep tests were conducted by using an improved triaxial creep apparatus. The results indicate that the creep behavior of BRM is significant with confining and deviatoric stresses being critical factors. The creep strain is in a nonlinear relationship with stress and time, and a larger deviator stress will lead to a larger creep strain. The main failure mechanism of BRM is plastic shear, accompanied by a significant compression and ductile dilatancy. Based on the test results, two well-established creep models, the Burgers creep model and Singh–Mitchell creep model, were used to comparatively analyze the creep behavior of the Bayer red mud under a certain stress level. Then, an improved Burgers creep damage constitutive model with the addition of a damage variable was proposed, whose parameters were also analyzed in detail. The comparison of the calculated values of the creep model and the experimental values shows that the proposed creep damage model can better describe the instant elastic deformation, attenuation creep, steady-state creep, and accelerated creep stages of the Bayer red mud.

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Experimental and Theoretical Studies on the Creep Behavior of Bayer Red Mud

Experimental and Theoretical Studies on the Creep Behavior of Bayer Red Mud Baoyun Zhao,1,2 Wei Huang,1,2 Zhile Shu,3 Mengmeng Han,4 and Yanbo Feng5 1School of Civil Engineering and Architecture, Chongqing University of Science and Technology, Chongqing 401331, China 2Chongqing Key Laboratory of Energy Engineering Mechanics and Disaster Prevention and Mitigation, Chongqing 401331, China 3School of Civil and Environmental Engineering, Xihua University, Chengdu 610039, China 4Chongqing Test Center of Geology and Minerals, Chongqing 400042, China 5School of Civil Engineering and Architecture, Chongqing University of Arts and Sciences, Chongqing 402160, China Correspondence should be addressed to Baoyun Zhao; moc.361@666nuyoab Received 11 January 2018; Accepted 29 March 2018; Published 2 May 2018 Academic Editor: Annan Zhou Copyright © 2018 Baoyun Zhao et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Abstract Long-term stability and safety of the Bayer red mud (BRM) disposal field is very important for the local residents’ life, which necessitates the knowledge of its creep behavior. In order to investigate the creep behavior of BRM, a series of triaxial drained creep tests were conducted by using an improved triaxial creep apparatus. The results indicate that the creep behavior of BRM is significant with confining and deviatoric stresses being critical factors. The creep strain is in a nonlinear relationship with stress and time, and a larger deviator stress will lead to a larger creep strain. The main failure mechanism of BRM is plastic shear, accompanied by a significant compression and ductile dilatancy. Based on the test results, two well-established creep models, the Burgers creep model and Singh–Mitchell creep model, were used to comparatively analyze the creep behavior of the Bayer red mud under a certain stress level. Then, an improved Burgers creep damage constitutive model with the addition of a damage variable was proposed, whose parameters were also analyzed in detail. The comparison of the calculated values of the creep model and the experimental values shows that the proposed creep damage model can better describe the instant elastic deformation, attenuation creep, steady-state creep, and accelerated creep stages of the Bayer red mud. 1. Introduction The Bayer red mud (BRM), also called as bauxite residue, is a hazardous solid waste generated during the Bayer alumina extraction from bauxite ore [1, 2]. It generally exists as a highly alkaline slurry (Ph 10–12.5) that is appropriately regarded as a hazardous material [3]. As there is a great deal of industrial alkali, fluoride, heavy metals, and other potential pollutants in red mud, long-term stockpiling would not only occupy scarce land resources but also easily lead to serious pollution of the surrounding soil, air, and groundwater [4]. In the past 50 years, the wet process was used to stockpile the Bayer red mud in Guizhou Aluminum Factory red mud disposal field, which led to much unconsolidated BRM in the disposal field. At present, the production technique has been upgraded to the sintering method, more and more dried red mud was stockpiled on the unconsolidated ones directly, which much exceed the original design storage capacity. Therefore, to make disposal field stable when renewing the dry red mud, we must evaluate the long-term stability of the original Bayer red mud. Good mechanical performance and especially creep behavior of the BRM is essential for safe and stable operation of such disposal field. Many laboratory studies investigated the creep behavior of various soils [5–7]. Yu et al. [8] performed several creep tests (lasting more than one year) to study the delayed mechanical behavior of Boom clay under the hydromechanical coupling effect. Wen and Jiang [9] discussed creep behavior of natural clayey soil with gravel at the residual state through a series of creep shear tests. Liao et al. [10] conducted a series of triaxial creep on warm frozen silts extracted from Qinghai–Tibet Plateau at a temperature of −1.5°C under the confining pressures of 0.5, 1.0, and 2.0 MPa, respectively. Karimpour and Lade [5] performed triaxial compression tests on dense specimens of Virginia Beach sand at low and high confining pressures to study time effects that relate to grain crushing due to static fatigue or delayed fracture. The abovementioned experimental studies mostly investigated clay, sand, and frozen silts. However, concerning the study of creep mechanical behavior of the Bayer red mud, little experimental data have been reported. Therefore, studies focusing on the Bayer red mud are needed to further our understanding of its creep mechanical behavior. Based on experimental investigations, various viscoelastic-plastic models [11, 12] taking into account soil an (...truncated)


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Baoyun Zhao, Wei Huang, Zhile Shu, Mengmeng Han, Yanbo Feng. Experimental and Theoretical Studies on the Creep Behavior of Bayer Red Mud, Advances in Civil Engineering, 2018, 2018, DOI: 10.1155/2018/6327971