Three-dimensional strata movement around coal face of steeply dipping seam group

Steeply dipping seam group,which has complex occurrence conditions,be- longs to the steeply dipping seam.The research on the strata movement around the coal face not only improves safe production technology in practice,but also develops the min- ing theory.By using physical simulation experiments,numerical simulation and site test, the deformation,failure and movement of surrounding rock in longwall working face were analyzed.According to the analysis,characteristics of the seam group were formed which is different from the single seam.Asymmetry mechanics,sequential changes and imbal- ance of strata movement along the tendency working face were summarized.Furthermore the features of upper and lower seams were different.The mining of the lower seam in- duced more complex strata movement along the strike.Multi-section mining disturbed surrounding rocks in larger areas than the single section mining did,which had an impact on and dynamic loading function to the support when mining the lower seam,and pro- duced a great influence on the stability of support-rock system.