Abstract
There are various complex joints (fissures), laminae, and other soft structural surfaces in the roadway enclosure, and the existence of these soft structural surfaces seriously affects the stability of the roadway enclosure. In order to study the mechanical properties of the coal body and the development of joints during coal fracture, this paper establishes a three‐dimensional model of the fracture structure of the coal body based on CT scanning and three‐dimensional reconstruction technology. On this basis, a 3D numerical model of the equivalent nodal coal body is constructed, uniaxial compression simulation analysis is performed, and the joint evolution development law of the coal sample is studied by the built‐in joint monitoring program of PFC3D. The results show that the larger the effective joint area and larger the joint size inside the coal sample, the smaller the compressive strength of the coal sample. The increase of joint size and joint surface area increased the ductility and stress‐strain curve multipeak phenomenon of the coal sample to some extent. During the rupture of the coal sample, the changes of each phase of the statistical curve of joint number and the phases of the stress‐strain curve of the coal sample are compatible.
Highlights
Coal body is a kind of heterogeneous geological body with complex composition and containing many kinds of fissures, in which the complex occurrence, trace length, and density of joints are the main factors that determine the mechanical properties and deformation law of coal and rock mass
Song et al combined the electron microscopy scanning technique and RFPA3D to conduct a fine view test of joint extension in barite containing a single pore, and the results showed that nonhomogeneity has a large influence on the joint extension characteristics in rock samples [17,18,19]; Asadizadeh et al studied the influence of the original joint structure on the macroscopic joint characteristics of coal and rock based on CT scanning technology and obtained the different three-dimensional fractal dimensions of the internal damage fracture surface of coal and rock specimens under different confining pressures [20]; Song et al studied the influence of different joint parameters on the rock strength by 3DEC numerical simulation software and analyzed the sensitivity of the rock strength to each parameter [21]
The above methods can simulate the nonhomogeneity of body, the constructed nodular coal body model does not have much research on the morphology and distribution characteristics of the irregular structure of joints in coal body. erefore, this paper mainly obtains the internal joints microstructure of coal body based on CT scanning technology, uses mathematical methods to process and analyze the extracted internal joints, and combines Avizo software and PFC3D to realize 3D reconstruction of coal body joints. e influence of coal body joints on the mechanical behavior of coal body such as compressive strength and deformation law is studied in depth, which provides a method to further understand the influence of coal rock joints structure on its mechanism
Summary
Coal body is a kind of heterogeneous geological body with complex composition and containing many kinds of fissures (joints), in which the complex occurrence, trace length, and density of joints are the main factors that determine the mechanical properties and deformation law of coal and rock mass. With the development of technology, some scholars obtained microfine information such as joint rate, joint occurrence, and internal images of coal rock bodies through CT scan and studied the influence of fine structure within coal rock bodies on their mechanical properties by combining with numerical analysis methods. In the current research process, the study of the mechanical properties and damage modes of joints on coal rock body mainly adopts physical methods and numerical simulation to establish the model of coal body containing small amount of, prefabricated, and through joints, and studies the damage mechanism of coal body by conducting uniaxial or triaxial compression test. The above methods can simulate the nonhomogeneity of body, the constructed nodular coal body model does not have much research on the morphology and distribution characteristics of the irregular structure of joints in coal body. erefore, this paper mainly obtains the internal joints microstructure of coal body based on CT scanning technology, uses mathematical methods to process and analyze the extracted internal joints, and combines Avizo software and PFC3D to realize 3D reconstruction of coal body joints. e influence of coal body joints on the mechanical behavior of coal body such as compressive strength and deformation law is studied in depth, which provides a method to further understand the influence of coal rock joints structure on its mechanism
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