Experimental study on reinforced effect of bolts on 3D surface fractured rock under uniaxial tension

Modified rubber powder-cement mortar is used to simulate the real rock. Glass fiber reinforced plastics (GFRP) is chosen as the bolt material. The reinforced and crack arresting effect of bolts on 3D surface fractured rock is studied. The experimental results show that the bolts obviously enhance the deformation modulus and uniaxial tensile strength. The deformation modulus increases with the increase of the anchor angles. The uniaxial tensile strength increases firstly, then decreases with the increase of the anchor angles, and it has the largest increment when the anchor angle β=45°. Due to the anti-slip and anti-shear properties of bolts, the fragile failure can be avoided for the fractured rockmass. Compared with the fractured specimens without bolts, there still exist different residual strengths after the pre-existing crack initiation for those specimens reinforced by the bolts with different anchor angles. Under uniaxial tensile conditions, the failure of reinforced specimens and non-reinforced specimens begins with the wing cracks at the tips of pre-existing cracks and the growth direction of wing cracks is approximately vertical to axial tensile stress. Secondary cracks appear when the anchor angle is smaller than a critical value. Under uniaxial tensile conditions, the failure mechanism of fractured specimens is the coalescence role of tensile crack.