Instability Model of a Coal Wall with Large Mining Height under Excavation Unloading Conditions

<div>Unloading stress field in the coal body at the coal wall. Force diagram of the (a) coal body and (b) coal units at the coal wall on the working face.</div>

Advances in Civil Engineering

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Figure 2

Figure 2: Instability Model of a Coal Wall with Large Mining Height under Excavation Unloading Conditions 