Mechanical Model and Parameter Optimization of Bolt-Shotcrete Support on Non-Straight Wall Part of Roadway

The bolt-shotcrete support of roadway is generally calculated by beam model, but the mechanical state of bolt-shotcrete support on the curved side of the roadway is obviously different from that on the straight side. The force of the shotcrete layer is analyzed in order to reasonably determine the bolt-shotcrete support parameters of the curved side of the roadway. The bolt-shotcrete support structure is simplified as a mechanical model of coupling between a fixed-end beam and a cylinder. This study undertakes a stress analysis of a shotcrete layer in order to find the mechanical mechanism of bolt-shotcrete support in a circular roadway (or the arc part of the roadway), and reasonably determine the parameters of bolt-shotcrete support. The bolt-shotcrete supporting structure is simplified as a mechanical model of the coupling between a fixed-end beam and a cylinder. The mechanical model for the influence of shotcrete layer thickness, shotcrete strength, bolt spacing and bolt length on the self-supporting capacity of the surrounding rock is established in combination with the Mohr-Coulomb strength theory. The influential law of the parameters of bolt-shotcrete support and the self-supporting capacity of the surrounding rock is determined. The results show the existence of a linear relationship between the strength of the shotcrete and the self-supporting capacity of the surrounding rock. A quadratic function relationship between the thickness of shotcrete and the self-supporting capacity of the surrounding rock is found. The results also show a cubic function relationship between the spacing and length of the bolt and the self-supporting capacity of the surrounding rock. The research results have a certain guiding significance for the determination of bolt-shotcrete support parameters on the curved side of roadway.