Figure 5 shows the vertical stress in the middle of the working face with different distances from fault when the footwall working face is advancing towards the fault.
Compared to the footwall working face, the roof and floor stress concentration degree of the hanging wall working face is higher.
When the footwall working face is advancing to the fault, inside the fault, the overlying strata are wedge-shaped; the abutment pressure and the vertical stress of surrounding rock increases first and subsequently decrease.
DISTRIBUTION CHARACTERISTICS OF ELASTIC ENERGY DURING FOOTWALL MINING
Figure 7 shows the distribution of the coal and rock elastic properties with different distance to fault when the footwall working face is advancing towards the fault.
Figure 8 shows the distribution of the elastic energy in the central part of the working face when the footwall working face is heading towards the fault.
Compared to the footwall mining, the energy concentration degree in front of the working face when mining in hanging wall is greater than that of mining in footwall, and the energy distribution is relatively uniform in the direction of inclination (Fig.
The energy concentration degree in the front of the working face is also higher than that in the footwall working face.
FAULT ACTIVATION HAZARD ANALYSIS DURING FOOTWALL MINING
Therefore, for the footwall mining, high-located rock strata fault activation precedes the immediate roof.
FAULT ENERGY EVOLUTION CHARACTERISTICS DURING FOOTWALL MINING
We can see from Figure 14 that the stress variation in the hanging wall mining fault zone and the footwall mining is different.