Fractal Study on the Failure Evolution of Concrete Material with Single Flaw Based on DIP Technique

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.

Fractal Analysis of Failure Process and Damage Evolution of Jointed Sandstone Based on DIP Technique

“…where φ represents the friction angle, σ 1 and σ 3 represent the primary stresses, and fc represents the uniaxial compressive strength. Under uniaxial compression, the damage variable ε of element can be represented as follows [24,25]:…”

“…where λ represents the residual strength coefficient, defined as ftr/ft � fcr/fc � λ, and εt0 represents the compressive strain at the elastic limit, which can be calculated as [24,25]:…”

“…e mesoscopic fracture process of jointed sandstone was simulated using RFPA2D software and digital image processing technology (see Section 2.1 of this article) in this work. rough twodimensional FEM, RFPA 2D can model the mesoscopic failure mechanism of rock [16,17,[22][23][24][25], and Section 2.2 shows the constitutive model of damage to the element. e actual size of this experimental model is 40 mm × 100 mm.…”

Fractal Study of the Development Law of Mining Cracks

“…Cai [19] used the improved box counting method to measure the dynamic characterization of the extension of the fracture network in porous media, and the fractal dimensions of the fracture network were related to drying time, average pore size, moisture content, and fracture porosity, respectively. Zheng [20] combined digital image processing technology and a rock failure process analysis system to study the influence of fracture geometric distribution and microscopic heterogeneity on material structure and proposed a damage variable index based on fractal theory. Chen et al [21,22] introduced fractal dimension to describe fracture surfaces with complex geometries and established a functional relationship between rock fracture bulk density and fractal dimension.…”

Characterization of Rutting Damage by the Change of Air-Void Characteristics in the Asphalt Mixture Based on Two-Dimensional Image Analysis

“…Researchers have been able to use digital image technology to monitor the internal failure process of engineering materials and connect this failure with the measured strain. Internal failure in materials can be represented in many forms, such as specific voids [ 5 ], crack surfaces [ 6 , 7 ], and spacing between cracks [ 8 , 9 ]. Air voids play an important role in characterizing the performance of asphalt mixture, and their distribution is very important for determining the overall mechanical response of asphalt mixture [ 10 , 11 , 12 ].…”