Inversion method of mechanical parameters of rock mass insoft rock roadway and its engineering applicatio

In order to improve calculation efficiency of underground rock engineering parameters, displacement inversion calculation of rock mass parameters was carried out by orthogonal experiment. An optimal model of equivalent mechanical parameters of roadway rock mass was established taking elastic modulus, cohesion force, internal friction angle and tensile strength of rock mass as test parameters. Based on field monitoring data of －850 m horizontal soft rock haulage roadway in Qujiang Coal Mine, function relationship between step displacement and rock mass parameters was established accurately using the established numerical model for numerical analysis and regression analysis. The equivalent rock mass parameter identification results show that at the location of 1 500 m of the east roadway, the safety factor Fs is 0.97 under the original supporting condition, which is in unstable state, so it is necessary to re—strengthen the supporting. Finally, stability evaluation of －850 m horizontal east haulage reworking roadway in Qujiang Coal Mine was carried out. The monitoring data of the roadway in the test section shows that the mechanical strength of the surrounding rock mass after the repair of east roadway is greatly improved, and the safety factor Fs is 1.58, which shows the roadway is in a stable state. It is indicated that the repair scheme of "screw, metal mesh, shotcrete, anchor cable, grouting and floor anchor cable" can well inhibit deformation of the roadway, which also verifies effectiveness of the rock mass mechanical parameter inversion method in soft rock roadway.