Abstract
While universal discrete element code (UDEC) is widely used for understanding the mechanism of large-scale strata movement and the effects of mining subsidence on the environment, the fundamental knowledge of how to set vertical joint spacing (VJS) in UDEC is still not fully understood. To address the knowledge gap, we first present a novel VJS calculation method, then conduct UDEC experiments, and finally compare the predictions of UDEC models with field subsidence observation. The results suggest the following: (1) when compared to the conventional VJS setting (1× to 3× bed thickness), the maximum surface subsidence (MSS) prediction via UDEC models based on our proposed VJS setting method is closer to field observation; (2) a smaller but varying VJS setting can also have the effect of a larger VJS setting; and (3) with the increase in VJS, MSS first drops, then rises, and reaches the minimum when VJS is set at approximately 7× bed thickness. This paper provides an explanation of the VJS setting in UDEC and establishes a bridge between the KS theory and VJS, which is helpful for the sustainable development of such an UDEC modeling strategy and for a better understanding of the influences of mining subsidence on the environment in mining-affected areas.
Highlights
Since there is no related theory in this regard for and the real existence of evenly spaced vertical joints (ESVJs) in the field is very rare as we have stated in the Introduction, we believe that assuming the vertical joint spacing (VJS) is essentially the same as the length of broken block in the
In general, the maximum surface subsidence (MSS) predicted by the universal discrete element code (UDEC) models based on borehole
We find that with the increase in the VJS, the MSS first drops, rises, and reaches the minimum approximately at 7× bed thickness
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Underground coal mining causes the deformation and movement of overlying strata and eventually leads to ground surface subsidence or cracking, which affects our living environment and the sustainable development of coal industries [1,2]. The discrete element commercial software UDEC is extensively used for understanding the mechanism behind strata movement and to predict surface subsidence more directly and realistically. The knowledge of how to establish a sound UDEC model especially involving discontinuity parameters is not entirely understood and merits further study. Modeling Prototype and Field Observation Prototype and Field Subsidence. Our UDEC experiments are based on Observation the Ying-Pan-Hao (YPH) coal mine located in the Wu-Shen banner of China’s Inner.
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