Abstract: For the close coal seam, the lower coal seam roadway is always influenced by the the upper coal seam, the roof strata of the close coal seam is damaged in different degree, It is so difficult to support the roof strata because its integrity is relatively poor.According to these problems,the discrete element software UDEC is adopted to analyze the failure characteristics of the lower coal seam roofs under the conditions of the difference of two layers coal interlayer thickness. Besides that, the the stability of mining roadway is also analyzed based on UDEC. Therefore, the research results can provide theoretical support for selecting the reasonable supporting pattern and designing the supporting parameters.

Key words: UDEC, Close coal seam, Infrabasal plate of mined-out area, Failure characteristics of infrabasal plate