Simulation Study On Mechanical Performances And Affecting Factors To Bolted Rock Mass

This paper focuses on the mechanics properties of bolted rock mass of the tunnel, combined with the methods of theoretical analysis, numerical simulation and analogy simulation tests, makes in-depth study of the mechanics properties which is caused by pretension-bolt.research contents include analogy simulation and numerical simulation on mechanical performances, analogy simulation to focuses on the distribution of the rock stress field and displacement field after the excavation, and under different confining pressure, the impact which the bolt pretension produced to bolted rock mass stress field.Mains conclusions:(1) This paper presents the main stress calculation at any point of bolted rock mass, and obtains the key parameters affecting the shape of the anchored-body supporting stress field;(2) After the excavation, the anchored-body radial stress field is in the tensile stress state,and the lateral stress field is in the compressive stress condition on account of the bounded constraint;(3) The area nearing the bolt of the anchored-body will form a "bottle" type effective compressive stress area which is about3-4times width of the tray. The stress in the front1/2of the free-section accounts for about5%-10%of the maximum compressive stress, the minimum stress in the middle of the free-section occupies for about1%, And the stress in the boundary part between the back of the free-section and the anchored-section is about5%; The tail of the bolt will form a ellipsoid shape of tensile stress region in a small range, with the bolt preload increases, the lateral width of the zone is reduced while the longitudinal length increases also with a movement to the central anchored-section;(4)A certain lateral squeezing action was produced within the range of2-3times the width of the tray nearing the anchored-area by the bolt;(5) The stress value of the anchored-body supporting stress field increasing as the bolt preload increases, meanwhile the diffusion range of anchored-body’s stress field is also increasing, but the distribution shape of anchored-body stress field is not affected by the bolt pretension;(6)The confining pressure has a certain weakening effect on the anchored-body supporting stress field.