Evolution law of water-conducting fault zone in large mining height working face under sandstone aquifer of Luohe Formation

Abstract

Aiming at the problem of safe coal mining under the sandstone aquifer covering Luohe Formation in the thick coal seam mining face of Xunyao Mining Area, theoretical analysis, similar material test and numerical simulation were used to study the overlying rock fracture and fracture evolution of large mining height in 1109 mining face. The results indicate that: under the condition of fully mechanized caving mining, overburden strata has experienced 5 changes, immediate roof broken, basic roof broken, basic roof periodic broken, key strata broken and key strata periodic broken. The density and width of fracture above working face will have a leap when the overburden rock is broken. In this process, the mining-induced fractures also have experienced 5 dynamic changes: preparation, production, stretch, close and compaction; many cracks will generate on fracture zone top, working face top and open-off cuts top in the course from open-off cuts to the full mining stage. The crack area which spreads around compacting area is parabolic shape. Namely, the cracks in central zone of overburden strata will close easily but the cracks in border zone will not; after the working face is fully excavated, the height of the water-conducting fissure zone is about 82 m to 85 m, and the sandstone overlying Luohe Formation is not connected.

Keywords

• luohe sandstone formation
• high mining height working face
• water flowing fractured zone
• similar material test
• numerical simulation