Abstract
Crack inclination and material heterogeneity have important effects on the meso-mechanical mechanism and macroscopic mechanical behavior of rock-like materials. In order to study the failure characteristics of shotcrete body during the process of using shotcrete bolt mesh support in the deep fractured rock mass of Lannigou Gold Mine, this paper combined the Digital Image Processing Technique (DIP) and RFPA2D (Rock Failure Process Analysis System) to establish a real meso-structure numerical model of concrete with different inclination angle cracks, simulating its crack propagation law and failure process, and studied the influence of crack geometry distribution and meso-heterogeneity on the effect of concrete structure. The findings reveal that the crack inclination angle has a substantial impact on concrete materials' compressive strength and elastic modulus, and both of them all show a nonlinear increase with the increase of crack angle; Because of the inhomogeneity of the materials, the inclination and propagation pathways of wing cracks are random, and the aggregate inhibits crack initiation and propagation. The wing crack's initiation position moves closer to the tip as the crack inclination angle increases, and the length gets shorter; Acoustic emission(AE) evolution characteristics are similar in samples with varying dip angles. In the early stages of loading, the AE energy is minimal, and increases rapidly when approaching the peak stress. The fractal dimension was used to describe the damage evolution process inside the material, and a damage variable index (ω) based on the fractal theory was proposed. The more the ω, the greater the material's degree of degradation. The proposed index provided a new method for quantitative study of the damage evolution characteristics of rock-like materials. It has guiding significance for the research on the stability of wet shotcrete in the deep fractured rock mass of Lannigou Gold Mine.
Highlights
Introduction e Lannigou GoldMine is located in Zhenfeng county, the Southwest of Guizhou province. e underground mining utilizes ramp development and layered upward cemented fill mining
Wet shotcrete is the most important process to reinforce the roadways, which is effective in the weathered rock mass of the mine
As a result, investigating the fracture characteristics and damage development process of wet shotcrete can provide some theoretical support for the concrete support of the Lannigou gold mine and other comparable mines
Summary
E value divides the distribution of each medium, and the non-uniformity characterization image of the material can be obtained [5, 19]. E non-uniformity characterization of digital image processing technology must be constructed with a finite element mesh and incorporated into the numerical model so that the influence of the material meso-structure may be considered in mechanical calculations and analyses. Is is due to the prefabricated cracks with different inclination angles in the specimen and the different mechanical properties of different components in the material, which lead to different mechanical responses under the same level of loading conditions, resulting in uneven stress distribution.
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