Study On High Convex Strip And Bolt-mesh-cable Combined Supporting Effect For Deep Soft Rock Roadway

Based on perfect reinforcement effect of high convex strip-bolting support technology achieved by a soft rock roadway at -420 level (depth of 640m) in Hebi No.9 Coal Mine, theoretical analysis, numerical simulation with FLAC3D, nonlinear prediction of surrounding rock displacement by LS-SVM, and in comjunction with inversion techniques of in-situ monitoring were carried out in our study.The following is the main research contents and the results in this dissertation.1.In accordance with the statistics of coal roadway support from main journals during last 30 years in China, though bolting support, especially combined support, has been widely applied, there exist deficiencies in studies of strip. In this paper, the roadway support technology was categorized into traditional support, metal support, bolting support and combined support, of which the characteristics and applications are totally analyzed.2.Theoretical formulas of high convex strip-bolting support parameters are raised. It is concluded that the convex bed of strip-band can adapt to large deformation of high pre-stressed bolting, and that the high strength and rigidity of strip can bear extremely large axial force and moment.3.The FLAC3D numerical simulation model of roadway section using the high convex strip-bolting support has been established. Considering the conditions of no support, general bolting support and high convex strip-bolting support, several regular conclusions of high convex strip-bolting support are put forward.4.The rock type of Permo-Carboniferous coal-bearing formation is classified as five kinds which are sandstone, siltstone, sandy mudstone, mudstone and coal. In-situ check and mechanical parameters of carboniferous rock are induced. The mechanical parameters for numerical simulation with FLAC3D are designed on the basis of Hoek-Brown criterion, RMR value score, and Chinese National Standards for Engineering Rock Mass Classification. By means of the analyses of the roadway deformation and strip strength conditions, surrounding rock classification of combined support of high convex strip-bolting is stated.5.Nonlinear predicted models of deep rock roadway basing on the LS-SVM are established, and the relevant Matlab codes are compiled. It is shown that nonlinear deformation predicted by LS-SVM is suitable for roadways excavated in deep weak rock masses.6.To take a haulage roadway at -420 level (depth of 640 m) in Hebi No.9 Coal Mine as an example, a design scheme is brought forward to fit for the deep roadway support. By successive observation and analysis of the convergence of roadway, the correctness, effectiveness and scientificalness of this study are further confirmed.