Experimental study on mechanical properties of anchorage body and on anchorage mechanism

A triaxial loading physical similarity simulation test system was developed for studying the anchorage effect of bolt on the surrounding rock of deep roadway,the anchoring effect of bolting density and pretension on pre-splitting specimen was analyzed,and the plate-beam model was established. The test results show that the specimens appear brittle failure without bolting support,its post-peak bearing capacity increases and shows obvious ductility characteris- tics with the increase of bolting support density and pre-tightening force. When the displacement of specimens in the vertical direction is similar,its volumetric strain decreases with the increase of the bolting support density and pre- tightening force. The splitting failure occurs mainly along the direction of maximum principal stress ( vertical direc- tion). The tensile cracks are concentrated near the free surface and the shear cracks are concentrated far away from the free surface. Under the action of bolts,a similar plate-beam structure is formed,whose deflection is not only related to the mechanical properties and external loads,but also to the length and form of the plate-beam. The increase of bolting support density changes the form of plate-beam structure and reduces its deflection. The larger pre-tightening force can reduce the separation between plate-beams,and the discontinuous deformation of specimens is reduced. Therefore,the effect of bolt on surrounding rock of deep roadway is obvious,which can change the stress bearing condition of anchor- age surrounding rock,can enhance the integrity and flexibility of surrounding rock,and can effectively control the dis- continuous deformation of fractured surrounding rock.