Deformation and failure mechanism of retaining gangue structure in hard roof cutting and roadway formation

For the problem of retaining gangue bending and skewing in the process of hard roof cutting roadway, this paper takes the 11^# coal 1105 working face haulage roadway of Qiuji Coal Mine as the object of study and builds the mechanical model of gangue retaining in the whole process. Then the stress and deformation of the retaining gangue structure under the impact and extrusion of gangue are simulated with the numerical calculation software ABAQUS, respectively. The results show that the hard roof caving gangue has obvious punching characteristics, which can easily lead to the lateral bending of the retaining gangue, especially the upper part of the I-steel in retaining gangue, and can effectively reduce the deformation of the I-steel by imposing a lateral constraint on the top of the I-steel. The metal mesh will deform and produce large tensile stress on the adjacent I-steel under the extrusion of gangue, which is easy to cause overall instability. The deformation of the steel mesh will be significantly reduced when the spacing between I-steels is 800 mm. A new gangue retaining support scheme is proposed. According to field monitoring, the deformation of the waste rock slope under the new scheme has been reduced by about 49 %, which is in line with production safety requirements.