| Jurassic coalfields in shallow seam near years of research and results show that the number of coal mining,the main feature is the occurrence of shallow buried depth,thin bedrock and thick sand layer.In the past using room and pillar mining method is backward,the formation of a large number of room and pillar goaf,and close seam group the dynamic pressure of mining disasters has obvious.Based on the theoretical analysis,physical simulation method and numerical simulation experiment,the room and pillar mining overburden structure space,the stability of coal pillar,roof stress distribution,stress transfer and dynamic pressure control problem was studied.Through the physical simulation experiment reveals wide coal pillar under 3-1 coal mining roof breaking mechanism of dynamic pressure,because the real column mining residual coal pillar in mined out area,the key layer in the advancing direction of uneven force,when the key stratum is located in residual coal pillar below,the key layer easy to be slipped instability;when the key stratum is located between two residual coal pillar under the goaf,the key layer has been simulated.Rotary instability in 3.4m columns and 15 m isolation pillar by FLAC3 D numerical simulation software of 2-2 coal seam mining,found in the range of 3-1 over the coal seam in the 5m~10m should be force fluctuation curve Significantly decreased(0~6m)by the upper immediate roof coal pillar stress concentration is smaller,and directly overhead(6~15m)key layer by the upper residual coal pillar effect is obvious,2-2coal seam residual coal pillar affected depth is about 27 m.by the corresponding impact factors to determine the working resistance of support.Analysis of the prevention mechanism of dynamic pressure blasting deep hole pre,put forward dynamic pressure control technology,using KJ959 underground microseismic monitoring system,the ground uses storage YTZ-3 seismic instrument,in 3301 working face overburden pillar goaf of coal pillar was pre blasting,according to the micro seismic event location monitoring,inference.Pre detonation impact range,has good prevention effect in the field. |
