Formation and evolution of the near—far filed structure of overlying strata in shallow long wall face

Figures 1-4 show the process of the similar simulation experiment.

Figure 1 is the model diagram of first breakage of main roof. It shows that when the working face advanced to 48 m, the initial fracture of main roof occurs, and the first weighting interval is 48 m. Accompanying with the coalface advancing, the immediate roof remains caved basically (Ren 2010).