In Situ Investigation and Numerical Simulation of the Failure Depth of an Inclined Coal Seam Floor: A Case Study

The 1131 working face of the Yangcheng coal mine was used for a research demonstration to study the failure characteristics of an inclined coal seam floor. A numerical simulation was carried out using Flac(3D) software and a team-designed mining and failure observation system was used for an in situ investigation. The results included: (a) the failure characteristics along the inclined direction were consistent with that along the strike direction; the failure zone of the rock mass floor had an asymmetrical distribution, in that the lower plastic zone was large and the upper shaping zone was small; (b) The variation trend of the maximum principal stress was basically the same as the failure depth in the floor's plastic zone. The failure depth reached a maximum when the working face advanced to 200 m. (c) The field-measured maximum floor failure depth was 31.5 m, while that of the numerical simulation was 32.3 m, indicating the results of the system measurements are accurate.