Post-peak behaviour of rocks under cyclic loading using a double-criteria damage-controlled test method
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ORIGINAL PAPER
Post-peak behaviour of rocks under cyclic loading using a double-criteria damage-controlled test method Roohollah Shirani Faradonbeh 1
&
Abbas Taheri 1 & Murat Karakus 1
Received: 14 July 2020 / Accepted: 29 October 2020 # Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract Cyclic loading–induced hazards are severe instability problems concerning surface and underground geotechnical projects. Therefore, it is crucial to understand the rock failure mechanism under cyclic loading. An innovative double-criteria damagecontrolled testing method was proposed in this study to capture the complete stress–strain response of porous limestone, especially the post-peak behaviour, under systematic cyclic loading. The proposed test method was successful in applying the pre-peak cyclic loading and then in controlling the self-sustaining failure of rock during the post-peak cyclic loading. The results showed that the strength of the rock specimens slightly increased with an increase in the fatigue life in the pre-peak region due to cyclic loading–induced hardening. Additionally, a combination of class I and class II behaviours was observed in the post-peak region during the cyclic loading tests; the class II behaviour was more dominant by the increase in fatigue life in the pre-peak region. Damage evolution was assessed based on several parameters, such as the elastic modulus, energy dissipation ratio, damage variable and crack damage threshold stress, both in the pre-peak and post-peak regions. It was found that when the cyclic loading stress is not close to the peak strength, due to a coupled mechanism of dilatant microcracking and grain crushing and pore filling, quasi-elastic behaviour dominates the cyclic loading history, causing more elastic strain energy to accumulate in the specimens. Keywords Cyclic loading . Pre-peak and post-peak behaviour . Damage . Crack damage threshold stress . Strength hardening
Introduction Surface and underground structures are usually exposed to environmental and human-induced cyclic loadings such as earthquakes, wind, volcanism, drilling and blasting, mechanical excavation and mining seismicity, which threaten their long-term stability (Taheri et al. 2016; Munoz et al. 2016a). Therefore, it is necessary to evaluate the time-dependent behaviour of rocks under cyclic loading. In rock engineering, understanding the fatigue response of rocks is of particular
* Roohollah Shirani Faradonbeh [email protected] Abbas Taheri [email protected] Murat Karakus [email protected] 1
School of Civil, Environmental and Mining Engineering, The University of Adelaide, Adelaide, SA 5005, Australia
interest since rock stability conditions vary significantly under cyclic loading. A great majority of rock fatigue studies have reported on the reduction in rock strength due to cyclic loading (Bagde and Petroš 2005). However, there are very few studies that have illustrated strength hardening when the cyclic stress level is low enough
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