Prediction model and application of damage and deformation of surrounding rock in roadway under repeated disturbance
The stability of roadway plays a crucial role in coal mine ventilation and transportation.Regarding the calculation of the damage and deformation range of the surrounding rock in deep roadway under repeated disturbances,taking the Mati-gou Coal Mine's 3507 working face as the engineering background,based on the expression of nonlinear rock strength pa-rameters(internal friction angle and cohesion)and the relationship between the maximum axial force of the anchor rod,the radius of the plastic zone and loosening zone of the surrounding rock,the strength parameters and deformation and failure range of the surrounding rock in each stage of roadway construction are analyzed based on the different types of disturbances suffered by the surrounding rock during the roadway construction process,including the first weakening after excavation dis-turbance,the first reinforcement after initial support,the second weakening after pre-splitting blasting.Finally,using the plastic zone radius of the anchored rock mass as the equivalent secondary excavation radius,a prediction formula for the plastic zone and fracture zone range of the roadway surrounding rock after repeated disturbance damage was established.Fur-thermore,based on the strength parameter analysis and deformation failure range prediction formula under the repeated dis-turbance mentioned above,the plastic zone and fracture zone range of the entry after deep hole pre-splitting blasting in engi-neering practice are calculated,and a reasonable secondary reinforcement design scheme is provided.The results show that after the implementation of the secondary reinforcement plan,the deformation control effect of the surrounding rock in the re-turn air entry is significant,reducing the deformation of the surrounding rock by 68％compared to before the secondary rein-forcement.
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