RESEARCH ON INFLUENCE OF OVERBURDEN PRIMARY KEY STRATUM MOVEMENT ON SURFACE SUBSIDENCE WITH IN-SITU DRILLING TEST

Based on the contrastive analysis between the in-situ test on interior rock movement and surface subsidence observation at working face No.31401 of Bulianta coal mine in Shendong mining area,the influences of overburden primary key stratum on surface subsidence are researched.The results indicate that the movement and deformation of overburden strata and surface are controlled by the primary key stratum,which is siltstone with the thickness of 47.01 m;and the movement of overburden strata changes periodically with the breakage of primary key stratum.Controlled by the primary key stratum,the subsidence velocity curves of the measuring points are influenced markedly by the measuring interval.The shorter the measuring interval is,the more obvious the periodical jumping change phenomenon of corresponding subsidence velocity curve is.Otherwise,the subsidence velocity curve is more even.Therefore,the measuring interval should be shortened in order to reflect the dynamic process of surface subsidence exactly in shallow coal seam mining;and then the inherent relationship between interior rock movement and surface subsidence can be realized correctly,which can promote the development of surface subsidence prediction.