As a consequence, the impact of each of the parameters on the potential for bumps is quantitatively classified in terms of a normalized intensity of plastic dissipated energy. After completion of the numerical experiments, statistical and multivariate analysis are performed using the calculated results from the orthogonal arrays to analyze the effect of these variables. In this study, orthogonal arrays, which were developed using the robust design, are used to define the combination of the (a) thickness of a stiff sandstone inserted on the top and bottom of a coal seam in a massive shale mine roof and floor, (b) location of the stiff sandstone inserted on the top and bottom of the coal seam, and (c) material properties of the stiff sandstone and contacts as interfaces using the 3-dimensional numerical model, FLAC3D. Therefore, to save time and honor the statistical distributions of the parameters, it is necessary to develop a robust design to collect sufficient sample data and develop a statistical analysis method to draw accurate conclusions from the collected data. Because the inherent variability of stratigraphic characteristics in sedimentary formations, such as thickness, engineering material properties, and location, is significant and the number of influential parameters in determining a parametric study is large, it is impractical to consider every simulation case by varying each parameter individually. This study describes the results of a robust design to consider the impact of different lithologic risk factors impacting dynamic failure risk. The effect of a stiff sandstone unit on the potential for coal bumps depends on the location of the stiff unit in the stratigraphic column, the relative stiffness and strength of other structural members, and stress concentrations caused by mining. Many conditions have been associated with bump potential, such as the presence of stiff units in the local geology. Despite significant advances in mine design tools and mining practices, these events continue to occur. from 1983 to 2014, there were 388 reportable bumps. For example, in just five states in the U.S. Is there a model models more suitable? I have seen anisotropic elasticity in the linear material properties, but it doesn't have different behavior in tension and compression.Bumps and other types of dynamic failure have been a persistent, worldwide problem in the underground coal mining industry, spanning decades. Model goes over elastic behavior, so it makes some iteration in plastic zone, but then it stops. After some iterations (depending on the moduli and yield strength) it's stop and the error is "Errore in element formulation". Anyway the solution doesn't stop immediately.
I have changed yield strength and elastic moduli, tangent moduli and time step but it doesn't work. Make the slopes more equal or possibly use a smaller time step". (with SOLID95)īut there is a problem, because it always appears errore: "TB,ANISO table has anisotropic yield stresses that not longer satisfy the consistency equation. Setting a low yield strength I thought it could works.
I have tried with TB,ANISO which permits a different behavior in plastic zone in compression and tension and it's anisotropic. I didn't find any solution in the range of elasticity. Instead, in the other two directions the behavior is the same, but the elastic modulus is different in tension(5GPa) and compression (2GPa). In the direction of fibers I have an elastic modulus that it's the same in compression and tension (about 10GPa). My material is a (unidirectional) composite, but I only know the mechanical properties of composite, and I don't know the fiber and matrix properties. I have to study a transversely isotropic material in ansys apdl.
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