Macro and Micro Structural Characteristics of Force Chains in Overlaying Strata Above Top Caving Mining Face
A study on force chains evolution of overburden strata and top coal is discontinuous system in full-mechanized caving mining, it has a great significance for mining pressure formation mechanism and pressure control. With the aid of biaxial loading and bia
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Abstract A study on force chains evolution of overburden strata and top coal is discontinuous system in full-mechanized caving mining, it has a great significance for mining pressure formation mechanism and pressure control. With the aid of biaxial loading and biaxial particle flow photoelastic experiment, the study on force chains forms in overburden strata-top coal and force chains evolution with the top coal drawing can be carried out. The result show that the distribution of force chains will presents horizontally with the particle drawing, and the density of force chains distribution increases gradually. The distribution of force chains in front of coal-drawing presents vertically, because of the pressure moving ahead and the concentration of force chains increases gradually. Because of the duplexing geological processes, the beam system is perfection than others, and the system is so solid.
1 Introduction Fully mechanized caving mining is one of the main ways for thick coal seam mining, since the 80’s of last century, it has been developing rapidly in our country [1], in fully mechanized caving mining, mine pressure and self weight to make the coal caving [2–4], and coal is drawing from coal-drawing back the support. Strata will fracture and top coal is destroyed cause by shear stress and pressure. Top coal will translate into granular by mine pressure and self weight, and overburden strata and top coal will form a loose discontinuous system. At the end of last century, Jin-an Wang Professor [5, 6] had discusses the mechanical properties of top coal medium state transformation for working surface support by researching in top coal X.G. Han (&) J.-A. Wang W.D. Pang C. Liang School of Civil and Environmental Engineering, University of Science and Technology Beijing, 30th Xueyuan Road, Haidian District, Beijing 100083, China e-mail: [email protected] J.-A. Wang State Key Laboratory of Education Ministry for High Efficient Mining and Safety of Metal Mines, Beijing, China © Springer Science+Business Media Singapore 2017 X. Li et al. (eds.), Proceedings of the 7th International Conference on Discrete Element Methods, Springer Proceedings in Physics 188, DOI 10.1007/978-981-10-1926-5_113
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movement rules and top coal medium state transformation mechanism, and proposed scheme for different top coal caving in different top coal At the beginning of this century, a discrete element calculation model of mining overburden strata was established by Jin-an Wang professor, overburden strata movement laws and change of stress field, characteristics of damage field was discussed in the process of full-mechanized caving mining. Large dip angle coal seam was simulated by Wang [7] with the aid of pfc2d, and overburden strata was established by particles bond side by side Wang [8–10] had carried out the simulation experiments of overburden strata-top coal,and the migration of top coal had been tracked and described. Chen [11] set up numerical model of roof-top coal by using the FLAC3D, and put forwa
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