Contraposing the phenomenon that strata behaviors were intense, and supports damaged or the tail beam and roof beam separated, it analyzed the overlying strata movement rule, structure feature and stress feature aroused by mountainous shallow-buried coal seam mining with distinct element software UDEC. When mountainous shallow-buried coal seam mined, the overlying strata up to the surface would collapse, fall, and the horizontal displacement along mountain slope was apparent. The overlying strata would form "two-zone" structure with transmitting horizontal stress relatively weak, the hinging relationship between the strata rocks or can not form hinging relationship, and can not form bearing structure with necessary bearing capacity by itself. The stress concentration range ahead of the face was small, but with higher maximum stress concentration factor, the weight of overlying strata that passed to preacted zone and coal seam ahead of face through the bearing structure was smaller, so the load on supports increased greatly.

Strata Behaviors in Mountainous Shallow-Buried Coal Seam Mining Working Face

Research on strata behaviors aroused by shallowburied coal seam mining and controlling of roof strata began in the early 1990s in China, and has got a series of achievements. Huang (2000, 2002) and Wang (2009) briefly divided Shallow-buried coal seams into two kinds: one was corresponded with flat terrain surface, with thick loose sand layer, thin bedrock (referred to flat shallow-buried coal seam in this paper). And the other was corresponded with mountainous terrain surface. This kind of coal seams outcrop was shallow, their loose sand layer was thin and thickness of bedrock varies greatly. The existing research mainly aimed at shallow-buried coal seams with thick loose layer, thin bedrock, and corresponded with flat terrain surface in Shendong mining area. The surface was regarded as plane, and the thickness of bedrock and loose layer was constant in research (see e.g., Qian and Shi (2003),Wang, Wang and Chen (2006), Li and Chen (2004), Huang (2005a,b), Lu (2007), Kang (2008), Zhao (2003) and Yin (2007)). However, less attention was paid to horizontal force in overlying strata. More attention should be paid to overlying strata structure and stress feature in mountainous shallow-buried coal seam mining in the research.

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