Abstract
Fracture toughness is an important fracture mechanics parameter of rocks, the double K criterion can reasonably explain the fracture mechanism of rocks. To investigate the fracture mechanics behavior of the anchored rock with a pre-crack, three-point bending test was performed to analyze the mode I fracture process of the rock. A series of pre-cracked sandstone beams of the same size, strength, and different anchor parameters were tested. The evolution characteristics of deformation field and crack tip propagation during the entire fracture process were investigated using a non-contact optical measurement method, and rock fracture mechanics parameters corresponding to different anchoring conditions were obtained. The toughening mechanism of anchor bolt was discussed based on stress intensity factor theory. The double K criterion can be used to describe the fracture failure characteristics of rocks. By regarding the anchored rock as the composite material of bolt and rock, the anchoring composite fracture toughness can be obtained, and the stability of the anchored rock can be determined using the double K criterion. The toughening mechanism of the anchor bolt increases the threshold of crack initiation and instability of the entire anchored rock by increasing the stress intensity factor at the crack tip of the rock. The crack arrest mechanism of the bolt retards crack propagation via the transverse closing force. Investigating the anchoring effect of different anchoring parameters allows, the rock anchoring control mechanism to be revealed from the perspective of fracture mechanics, which can provide a reference for mining and tunnel engineering support.
Published Version
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