Simulation of compression-induced shear-mode cracks in rocks based on experimental investigations performed on gypsum sp
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ORIGINAL PAPER
Simulation of compression-induced shear-mode cracks in rocks based on experimental investigations performed on gypsum specimens Jun Xu 1 & Xiaochun Xiao 1 & Xiangfeng Lv 2 & Pengfei Guo 3 & Yanyan Peng 3 Received: 22 September 2019 / Accepted: 27 April 2020 # Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract Compression-induced shear-mode cracks play an important role in the failure process of rocks. To gain insight into the compression-induced shear-mode cracks in rocks, the initiation and propagation of compression-induced shear-mode cracks are investigated via physical experiments and numerical simulations. The experimental results show that compression-induced shear-mode cracks are a common fracture mode and often lead to final failure. The initiation and propagation of compressioninduced shear-mode cracks, as well as the strength of the specimen, can be influenced by the spacing between the flaw tips. Compression-induced shear-mode cracks easily initiate and propagate when the spacing between the two pre-existing flaws is small, whereas a larger spacing can reduce the possibility of shear fracturing and is propitious to the generation of compressioninduced tensile-mode cracks. In addition, compression-induced shear-mode cracks initiate and generate later than compressioninduced tensile-mode cracks. Furthermore, the fracture angles of compression-induced shear-mode cracks are diverse and complex and can be influenced by the spacing between pre-existing flaws. Numerical simulation results suggest that compressive-shear failure initiates randomly in a shear stress field, becomes more localized with the increased loading and eventually results in compression-induced shear-mode cracks. Keywords Compression-induced shear-mode crack . Initiation and propagation . Crack pattern . Strength . Fracture angle
Introduction
* Xiaochun Xiao [email protected] * Xiangfeng Lv [email protected] Jun Xu [email protected] Pengfei Guo [email protected] Yanyan Peng [email protected] 1
School of Mechanics and Engineering, Liaoning Technical University, Fuxin 123000, China
2
School of Civil and Resource Engineering, University of Science and Technology Beijing, Beijing 100083, China
3
School of Civil Engineering, Shaoxing University, Shaoxing 312000, China
Fractures are usually closely related to the initial inhomogeneities (e.g. cracks, cavities and inclusions) and can be developed in any engineering structures, as shown in Fig. 1. In the process of fracture, crack initiation, propagation and coalescence often cause more cracking and deformation (Levy and Molinari 2010; Zhao et al. 2019; Ma et al. 2019). It is easy to see that the cracks in Fig. 1 are mostly shear-mode cracks, which are common fracture modes and often occur under compression or when the confining pressure is very small (or zero). These cracks are defined as compression-induced shear-mode cracks (CiSmCs) in this investigation. In many practical engineering situations, understanding the shear-mode cracking phenomena is of
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