Analysis of the Microstructure Stress Distribution and Deformation Characteristics of Coal via CT 3D Reconstruction Technology
- Gang Wang (Shandong University of Science and Technology) | Dongyang Han (Shandong University of Science and Technology / College of Mining and Safety Engineering) | Chenghao Jiang (Shandong University of Science and Technology / College of Mining and Safety Engineering) | Xiangjie Qin (Shandong University of Science and Technology / College of Mining and Safety Engineering)
- Document ID
- American Rock Mechanics Association
- 53rd U.S. Rock Mechanics/Geomechanics Symposium, 23-26 June, New York City, New York
- Publication Date
- Document Type
- Conference Paper
- 2019. American Rock Mechanics Association
- 4 in the last 30 days
- 32 since 2007
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ABSTRACT: In order to investigate the stress distribution characteristics and deformation failure law of micro-coal structure under loading, a digital model that can characterize the true pore structure of coal and rock mass is constructed by combining computed tomography (CT) scanning and 3D reconstruction. The digital model is simulated using the software ABAQUS and the Drucker–Prager constitutive model via uniaxial compression. Results show that stress concentration usually occurs under axial load. The stress distribution law of elliptical pores is related to the inclination of the pores. The tensile stress at the tip of the pore boundary is concentrated in the vertical pores. The stress type in the middle position of the pore boundary changes from tensile to compressive. The distribution law is contrary to that of the stress distribution in the vertical pores. Through the analysis of the stress distribution law of the pores under vertical and horizontal conditions, it is concluded that the inclination degree of the pore and fracture structure will have a certain impact on the cracking. This research reveals the stress of the pore structure of coal and rock mass and the variation law of fracture from a microscopic point of view.
Natural porous media, such as coal and rock bodies, are characterized by large number of pores, cross-distribution of pore size, and complex heterogeneity and anisotropy. and anisotropy. Their mechanical forms also exhibit and anisotropy. Their mechanical forms also exhibit and anisotropy. Their mechanical forms also exhibit complex nonlinearities (Kulenkampff, 2015, Vishal, 2013)[1-2]. Quantitatively characterizing the pore structure is crucial in studying the mechanical failure characteristics of rock mass during compression. It helps monitor and evaluate the stability of rock mass engineering and identify the criterion of rock engineering instability.
Studying the mechanical properties of pore structures is a research process that involves macroscopic and microscopic mechanisms. People often conduct physical experiments to study pores and fractures macroscopically. Shi et al., 2018 studied the short-time creep behavior of rectangular sandstone samples with two pre-existing cracks under uniaxial compression through acoustic emission (AE) experiments and analyzed the mechanical properties of samples with different crack lengths. Kong et al. 2016 and 2017[4-5] analyzed the time-varying AE law during coal rock loading and multifractal characteristics with load and time. Chen et al., 2017 conducted a uniaxial compression test on sandstone samples with double cracks and a single circular pore to investigate the relationship between the crack initiation form of the composite fractured rock sample and the fracture inclination angle (α). However, due to the microscopic nature of the pore structure and the complex disorder of its morphology, the distribution characteristics of the internal pore structure of coal and rock mass cannot be described accurately through physical experiments. Therefore, scholars have used numerical simulation methods to study the microstructure of coal. Jiang et al., 2015 used DEM discrete element to simulate the uniaxial compression of pre-formed fractures of granite, and studied the distribution of fissure stress during compression. Zhang et al., 2017 conducted a numerical analysis of the cracking of coal under sound pressure and surrounding rock stress and analyzed in detail the effect of ultrasonic on the cracks generated in physical experiments. However, due to the complexity and idealization of the model structure, the existence of pores and other structures in the rock mass structure was disregarded in the simulation, which reduced the accuracy of the simulation results.
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