Study of localized deformation in geopolymer cemented coal gangue-fly ash backfill based on the digital speckle correlation method

Sun, Qi; Cai, Chunhua; Shu-kun, Zhang; Tian, Shuai; Li, Bing; Xia, Yajie; Sun, Qingwei

doi:10.1016/j.conbuildmat.2019.04.208

Cited by 62 publications

(18 citation statements)

References 37 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…By comparing the lateral strain-time curves at different positions of the test sample, it can be concluded: the lateral expansion of the test sample under compression was not uniform; when the test sample was destroyed, the largest lateral deformation occurred at the middle of the specimen; the rapid growth of lateral localized deformation eventually led to the overall instability of the specimen (Sun et al 2019a).…”

Section: Step-by-step Loading Testmentioning

confidence: 99%

Deformation and instability properties of cemented gangue backfill column under step-by-step load in constructional backfill mining

Yao

Ran

Feng

et al. 2021

Environ Sci Pollut Res

View full text Add to dashboard Cite

Abastract：Constructional backfill mining with cemented gangue backfill column can solve the environmental issues caused by mining activities and the accumulation of waste gangue at a low cost. To study the deformation and instability properties of cemented gangue backfill columns during the advancement of coal mining face, five step-by-step loading paths were adapted to mimic the different loading processes of the roof. The lateral deformation at different heights and axial deformation of the sample were monitored. The results show that the deformation and instability of the backfill column have the properties of loading paths and are affected by the step-by-step loading path. When stress-strength ratio (SSR) is less than 0.6, the lateral of backfill column shrinks during the creeping process. In high-stress levels, lateral creep strain develops faster than axial creep strain. The backfill column has characteristics of axial creep hardening and lateral creep softening during the step-by-step loading process. The instantaneous deformation modulus and instantaneous Poisson's ratio show an upward trend. The bearing capacity of backfill column under the step-by-step load is related to loading paths and is no less than uniaxial compressive strength. The non-uniformity of the lateral deformation of backfill column leads to excessive localized deformation that mainly occurs in the middle, causing the overall instability. The development of cracks of backfill column under step-bystep load could be divided into 4 stages according to SSR. Under different step-by-step loading paths, the axial creep strain rate is nearly a constant before entering the accelerated creep stage. A nonlinear creep constitutive model with a creep strain rate trigger was proposed to depict the development of axial strain under step-by-step load. This research will provide a scientific reference for the design of the advancing distance and cycle for the hydraulic support, and reinforcement of the backfill column. Keywords：Cemented gangue backfill column; step-by-step load; deformation; instability; nonlinear creep constitutive model 1 IntroductionCemented gangue backfill mining technology is an important part of the "green mining" system for coal mining, it not only controls the movement of the overlying strata and the surface subsidence effectively, but also consumes a large amount of coal gangue (Chen et al. 2016a).The material used for coal mine backfill mining is made of coal gangue, cement, fly ash, and water. Generally, the method of full backfilling is used in coal mining, that is, all mined-out space is filled with cemented gangue backfill material. However, the cost of cement and fly ash is relatively high, and the production of coal gangue only accounts for about 20% of the output of raw coal (Liu et al. 2020). The high cost and limited raw materials impede the promotion of coal mine full backfill mining; thus, partial backfill mining (Zhu et al. 2017) and constructional backfill mining (Feng et al. 2019;Du et al. 2018) are proposed, and ...

show abstract

Section: Step-by-step Loading Testmentioning

confidence: 99%

Deformation and instability properties of cemented gangue backfill column under step-by-step load in constructional backfill mining

Yao

Ran

Feng

et al. 2021

Environ Sci Pollut Res

View full text Add to dashboard Cite

show abstract

“…e microstructure of the backfill dramatically impacts its macromechanical characters [25][26][27]. A good microstructure is the underlying reason behind the rather high earlier strength of the backfill.…”

Section: Microstructure Analysismentioning

confidence: 99%

Impact of Temperature on the Strength Development of the Tailing‐Waste Rock Backfill of a Gold Mine

Han

Zhang

Sun

2019

Advances in Civil Engineering

View full text Add to dashboard Cite

This study investigated the influencing rules of curing temperature (5, 10, 16, and 20°C), cement ratio (8%, 10%, 12%, and 14%), and mass concentration (70%, 73%, 74%, and 75%) on the strength of backfill. In addition, a scanning electron microscope (SEM) is employed to analyze the microtopography of the backfill. Experimental results indicate that the uniaxial compressive strength (UCS) of the backfill decreases as the curing temperature diminishes; temperature substantially influences the earlier strength of backfill (it is much significant below 10°C). In addition, as the cement ratio rises, the critical point for the impact of temperature on strength gradually moves toward a low-temperature zone; in pace with the slurry mass concentration increase, the compressive strength of the backfill also rises and its rate of increase enlarges after going beyond the critical concentration. In case the curing temperature is lower than 10°C, the extent of hydration is also low inside the backfill. Through experiments, the critical concentration of slurry in the Jinying gold mine is determined as 73%, and the critical interval of the cement ratio ranged between 10% and 12%. Corresponding measures can be taken to increase the strength of backfill in the Jinying Gold Mine by 129.9%. As a result, backfill collapse is effectively controlled.

show abstract

“…The accurate deformation (strain) measurement and the understanding of strain localisation behaviour are critical to evaluating CPB systems' damage evolution and failure mechanism. However, a literature survey indicates limited research has been reported on the accurate strain measurement and the understanding of strain localisation behaviour of CPB systems (Sun et al 2019;Zhao et al 2019).…”

Section: Introductionmentioning

confidence: 99%

Strain localisation behaviour of cemented paste backfill

Zhao¹,

Li²,

Taheri³

et al. 2021

Paste 2021: 24th International Conference on Paste, Thickened and Filtered Tailings

View full text Add to dashboard Cite

Mine tailings are the most significant and most problematic sources of solid waste globally in the mining industry. The developing concept of sustainable mining warrants reusing mine wastes, particularly tailings. Cemented paste backfill (CPB) is a backfill method composed of dewatered tailings, a cementitious binder, and processed mine water. CPB reuses tailings in underground mine excavations, and as such, reduces the amount of surface-disposed tailings, mitigates the potential environmental impacts, and assists waste management. In this study, the strain localisation behaviour of a South Australian copper-gold underground mine CPB system was evaluated through a comprehensive experimental programme. Understanding the strain localisation behaviour helps evaluate CPB damage evolution and failure mechanism under real-life loading regimes. The three-dimensional digital image correlation (DIC) technique was used to measure the full-field of strain development on the surface of CPB samples during unconfined compressive strength (UCS) tests. With the use of several virtual extensometers, the axial and lateral strains of CPB samples, with and without strain localisation, in both pre-peak and post-peak regimes are characterised. Overall, the DIC technique provides more accurate stress-strain relations of CPB samples than conventional external measurement devices. The DIC test results indicate that strain localisation of CPB samples initiates in the pre-peak regime at around 80% of the UCS. The greater the binder content and the longer the curing time, the higher the axial stress level required to initiate localisation to the UCS, thus emulating the failure mechanism of quasi-brittle materials -rock and concrete. Finally, with the increase of curing time, the difference between strain values at the localised and non-localised zones became less significant in the pre-peak regime and more pronounced in the post-peak regime.

show abstract

Study of localized deformation in geopolymer cemented coal gangue-fly ash backfill based on the digital speckle correlation method

Cited by 62 publications

References 37 publications

Deformation and instability properties of cemented gangue backfill column under step-by-step load in constructional backfill mining

Deformation and instability properties of cemented gangue backfill column under step-by-step load in constructional backfill mining

Impact of Temperature on the Strength Development of the Tailing‐Waste Rock Backfill of a Gold Mine

Strain localisation behaviour of cemented paste backfill

Contact Info

Product

Resources

About