The Hydrogeological Characteristics of Thick Alluvium with High Water Level and the Influence on Zhaogu Mining Area, Henan Province, China

In parts of North China Plain, there are several aquifers in the thick alluvium over coal seam, which overlays a large amount resources. Roof water inrush accident occurred during mining often caused by multiple reasons. Based on case roof Zhaogu Mining Area, hydrologic supplementary exploration north flank, stratum data were obtained; combined with previous geological drilling mine, structural characteristics five main and aquicludes flank classified. By pumping test No. 1 2 drill holes, richness 5th aquifer is identified as medium level. Three thin layers gravel beneath found hole, lowest (2.95 m thickness) was followed test, reveals an important factor leading to insufficient size safety pillar. The leakage self-closed aperture sand soil aquiclude clarifies that fracture connection, it cannot resist crushing under high pressure aquifer. mechanism high-pressure working face supports, calculation method support resistance alluvial layer put forward, reason failure resistance, leads abnormal height caving. methods experiment clarified for preventing faces similar background.