Abstract
Uniaxial compression tests were conducted on marble specimens containing two flaws. There are coplanar flaws and noncoplanar flaws. The inclination angle and spacing of flaws were considered of the coplanar flaws model, and the step angle and spacing of flaws were considered of the noncoplanar flaws model. Strength failure and crack coalescence behaviour were analysed in the paper. The crack evolution process containing microcrack initiation, coalescence, and failure is focused on the rock bridge coalescence and the extent of the pre‐existing flaws. There are four forms of rock bridge coalescence: tensile crack coalescence, shear crack coalescence, mixed tensile and shear crack coalescence, and no coalescence. Also, there are four forms of the rock failure mode: tensile failure, shear failure, mixed tensile and shear failure, and split fracture. The outer end of the critical stress values were used to compare with the crack initiation strengths, and the crack initiation strengths were slightly larger than the critical stress. In addition, energy dissipation laws were analysed during the model fracturing process. The crack evolution mechanisms around the pre‐existing flaw in the model were revealed by the distribution of microcrack and energy dissipation.
Highlights
With the rapid development of civil and traffic engineering and the exhaustion of shallow resources and energy, many rock projects have entered deep environment; crack evolution lead to frequent instability failure accidents of rock mass underground engineering. e Jinping II Hydropower Station is located on the main stream of the Yalong River in the Liangshan Yi Autonomous Prefecture in Sichuan Province and is one of the backbone hydropower stations developed by the lower reaches of the Yalong River
Marble is the main surrounding rock of the Jinping II Hydropower Station. e fracture evolution process of the crack in the rock mass is an urgent scientific problem to be solved in deep underground rock engineering. erefore, we consider the pre-existing flaws in the model, and fracture mechanics and crack coalescence behaviour of the marble containing pre-existing flaws are researched
In addition to physical experimental studies, numerical simulation plays a major role in crack coalescence research
Summary
With the rapid development of civil and traffic engineering and the exhaustion of shallow resources and energy, many rock projects have entered deep environment; crack evolution lead to frequent instability failure accidents of rock mass underground engineering. e Jinping II Hydropower Station is located on the main stream of the Yalong River in the Liangshan Yi Autonomous Prefecture in Sichuan Province and is one of the backbone hydropower stations developed by the lower reaches of the Yalong River. Erefore, we consider the pre-existing flaws in the model, and fracture mechanics and crack coalescence behaviour of the marble containing pre-existing flaws are researched. The synthetic rock mass (SRM) approach has been employed for a more realistic simulation of jointed rock masses [12] In this approach, intact rock is represented by Bonded Particle Model (BPM), which has been extensively used for rock failure analyses over the past decade [3, 14]. Based on the DEM, the stress distribution status of the model in the process of loading at a different stage can be used to validation the real-time cracking evolution analysis. In addition to determining the crack initiation stress and crack damage stress, peak strength based on numerical calculation, the stress intensity factor, outer side critical stress, and internal side critical of flaws based on the fracture mechanics were used in this article. E critical stress based on the fracture mechanics was obtained, and fracture energy analysis was studied in this article
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