Experimental Research On Affecting Factors Of The Roof Anchorage Strata Stability Of The Coal Roadway

The roof accident of the coal mine during a single period usually don't like gas and permeable accidents, but it has a higher probability of occurrence. The casualties caused by it accounted for about 30% of the total casualties.The roof accident takes up large greater proportion in the " five big disasters ". Besides the more complicated surrounding conditions and coal mining technology conditions, the immaturity for the reinforcement and supporting theory of the surrounding rock is one of the important reasons causing this result. The roof accident in the extraction bears the bell in the roof accidents, therefore, exploring the correct roof supporting theory, selecting safe and reliable supporting method, seting economic reasonable supporting parameters and practical efficient construction craft have become a major theoretical and technical subject which people try to solve in the long term.Based on analog simulation experiment for the anchor system in the roof comprehensive consideration of the coal mine, through the roof similar simulation test in laboratory, on the basis of comprehensive analysis of previous theoretical achievements, this paper probed into the stability factors with the roof anchorage system in the roadway, and analyzed the mechanical mechanism of the anchor rock and stress distribution of anchorage system by theoretical analysis, laboratory analog simulation, and numerical simulation, etc.Through the research into the process, phenomenon and data of the experiment, and numerical simulation's validation, the paper obtained some very meaningful results, and found some neoteric problems. Summarized as follows:(1)Under the action of a certain Pre-tightening force,the deformation and destruction of the roof weakened and the subsidence reduced significantly, but the affected scope of the roof under the influence of excavation is a bit larger in a pre-stressed anchor compared to no anchor.(2)Under the same condition, considering the pre-tightening force, the bigger the pre-tightening force with the anchor, the smaller the deformation of the roadway, and the anchoring effect is better.(3) With the roadway excavation, the roof deformation increased gradually, the deformation in the center line of both sides in roof roadway is the symmetric distribution, the deformation of the centerline position is biggest. After the deformation, the roof can form the similar three hinge arch structure. (4) As the sliding instability of the anchor, the roof will sink, and with the increase of slippage, subsidence then increased, after the sliding deformation, the roof can form the similar three hinge arch structure; The position with the biggest subsidence located the roof centerline, and the subsidence reduced from the center to every help gradually.(5)The stress of the anchor with the width of the roadway excavation has a inflection point when the three hinge arch structure forms; After this inflection point, the stress of the anchor increases as the width of roadway excavation increases. The inflection point's existence with the stress of two anchors is the result of the three hinge arch structure's formation.(6) The stress of the anchor reduced with the increase of the anchor end's slippage. In engineering practice, if the anchor is anchored in soft rock or the anchorage force is insufficient, it will loose or sliding, then the stress of the anchor will reduce even fail.In addition, the test also found some problems, such as the stress of the anchor has a inflection point with the increase of roadway excavation's width, there will be a increase with the excavation, and the stress first increases, then decreases; The rheological properties of materials will be also a effect, etc.