Abstract
This paper develops a new statistic damage model for rock to mainly study the effect of a loading rate on its mechanical behaviours. The proposed model adopts a new loading rate-dependent damage density function and is capable of describing the macroscopic damage accumulation process for rock samples subjected to external high-speed dynamic loadings. The proposed model can also account for the residual strength of rocks by introducing a modified equivalent strain principle, which considers the contribution of the friction force to the strength of rocks. The friction force is generated by the movements of the nearby microcracks. The predicted stress-strain curves by the proposed model agree with the measured data of salty rock under the conditions of various confining pressures and loading rates. It can be found that both the peak strength and the corresponding axial strain are increased at high-speed loading conditions. At the same time, a transition from ductile failure to brittle failure can be observed in rock samples.
Highlights
Academic Editor: Bing Bai is paper develops a new statistic damage model for rock to mainly study the effect of a loading rate on its mechanical behaviours. e proposed model adopts a new loading rate-dependent damage density function and is capable of describing the macroscopic damage accumulation process for rock samples subjected to external high-speed dynamic loadings. e proposed model can account for the residual strength of rocks by introducing a modified equivalent strain principle, which considers the contribution of the friction force to the strength of rocks. e friction force is generated by the movements of the nearby microcracks. e predicted stress-strain curves by the proposed model agree with the measured data of salty rock under the conditions of various confining pressures and loading rates
Introduction e mechanical behaviours such as strength and deformation of rock are affected by loading rates [1,2,3,4]. e microcracks distributed inside the rock samples will be propagated and result in macroscopic damage [5,6,7,8,9]
E statistic damage models can account for the propagation process of microcracks and characterise the strength and deformation behaviours of rocks, which have been widely applied in geotechnical engineering. [22]developed a damage model to study the effect of freeze-thaw cycles and Advances in Civil Engineering confining pressures on the mechanical properties of rocks. [23] applied an equivalent continuum damage model for modelling the impact of weakness planes in rock masses on the stability of tunnels. e temperature may affect the mechanical properties, which can be described using the statistic damage theory [24,25,26]
Summary
Received December 2021; Revised 4 January 2022; Accepted January 2022; Published 9 February 2022. Is paper develops a new statistic damage model for rock to mainly study the effect of a loading rate on its mechanical behaviours. E proposed model adopts a new loading rate-dependent damage density function and is capable of describing the macroscopic damage accumulation process for rock samples subjected to external high-speed dynamic loadings. E statistic damage models can account for the propagation process of microcracks and characterise the strength and deformation behaviours of rocks, which have been widely applied in geotechnical engineering. Is paper aimed to develop a dynamic statistic damage model to study the effect of loading rates on rocks’ strength and deformation behaviours. The evolution law of the damage factor was assumed to be affected by the loading rates to describe the macroscopic damage accumulation process when the rock samples were subjected to external dynamic loading. The proposed model adopted the modified Lemaitre strain equivalence assumption to consider the residual strength of the rock. e proposed model was used to predict the experimental results of salt rock under different confining pressures and loading rate conditions
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