Control for the large section roadway under small abandoned mines in the same coal seam by secondary support.

To control roadway under small abandoned mines in ultrathick coal seam, this paper analyzed its deformation and failure characteristics. As a result, the roadway occurred roof leakage and right rib extrusion. Based on above characteristics, the secondary support schemes were put forward. To predict the control effects of the roadway, a numerical model was built to analyze its deformation under the secondary support schemes. Besides, the industrial test was carried out. From the test and numerical simulation, a significant increase could be found in vertical stress and bearing capacity on ribs after the secondary support. Moreover, under the secondary support, the roof separations of roadway decreased more than 90%, while the lateral displacements of the roadway dropped over 85%. Based on the above, it was indicated that the deformation of the roadway could be well controlled. [ABSTRACT FROM AUTHOR]