# An Investigation into Bol Anchoring Performance during Tunnel Construction in Bedded Rock Mass
###### Abstract  
The anchor bolt is a key point of tunnel design in bedded rock mass. The previous theory of anchorage support falls does not fulfil engineering requirements, and the stability of bedded rock must be addressed by empirical methods. To investigate the bolt anchoring performance for bedded rock mass under different anchoring methods, the rock failure mode under shear and tensile stresses in bedded rock was examined in this paper. The results showed that bolt anchoring for rock is achieved mainly through the bonded restoration of surrounding rock near the drill holes by means of an anchoring agent and the supporting resistance provided by the bolt body. It was observed that the strength parameters of bedded rock were increased under the anchoring effect. Full anchoring bolts were especially effective. In addition, it was observed that, in the absence of bolts, the failure form changed from shear to split. In the case of bolting, the failure plane occurred parallel to the bolt's axis. The shearing began along the interface between the hard and soft rock bedding. Compared to end bolt anchoring, full-length bolt anchoring was more capable of offering an anchoring effect. The latter offered a greater increase in the strength and greater shear-bearing capacity of the rock, which ultimately enabled the rock to bear more load. t 1 202020  
body (bolt) is inserted and screwed. In theory, the bolt and surrounding rock mass are bonded in full length via the anchoring agent; however, as the location and angle of the hole differ, bolt construction difficulties vary, especially for the tunnel arch part. Furthermore, it is difficult to ensure the grouting quality of the anchoring agent, which causes the anchorage length of the bolt to vary. Therefore, it is necessary to investigate the impact of anchoring and the stability effect of the jointed rock mass. The bolt reinforcement effect on jointed rock mass mainly enhances the shear-bearing capacity of the rock mass joint plane. In addition, it prevents the rock mass from developing an intercalated dislocation along the joint plane [11; 12]. Many factors affect the reinforcing effect of the bolt on the joint plane, such as the bolt size, hole diameter, pretension force, grouting, and anchored rock mass strength [13; 14; 15; 16; 17; 18; 19; 20; 21]. Many studies have been conducted on the above aspects. In 1974, [PERSON] [11] conducted systematic research on the shear property of granite under full-length anchoring and showed that the tangential shear-bearing capacity of the bolt can significantly enhance the stability of the jointed rock mass. [PERSON] et al. [22] and [PERSON] et al. [23] researched the impact of the bolt on the joint shear-bearing capacity of different rocks. Using anchorage tests of jointed rock mass, [PERSON] et al. [24], [PERSON] [25], and [PERSON] et al. [26] analyzed the impact of factors such as the quantity of bolts, elasticity modulus of the bolt body, bolt material, and roughness of the rock joint on the joint shear-bearing capacity. Moreover, [PERSON] et al. [27] theoretically analyzed the bolt shear-bearing capacity and evaluated the impact of the anchoring angle on the anchoring effect. [PERSON] [28] and [PERSON] et al. [29] conducted laboratory shear tests of anchored and jointed rock mass and employed numerical simulation methods to analyze the shear resistance effect of the bolt. They respectively showed that the bolt can form plastic hinges on the joint plane, and that bolt failures mainly occur among the plastic hinges soon thereafter. Meanwhile, [PERSON] et al. [30] conducted research on the deformation property of a pre-tensioned bolt during a shear test. They determined that the bolt shear-bearing effect occurred after the shear dislocation of the joint plane on account of the bolt \"dowelling function\". [PERSON] et al. [31] compared failure modes of end anchoring, full-length anchoring, and non-anchoring by experiment.