Abstract
Due to geological structure and artificial disturbance, a large number of joints and fissures are formed in the surrounding rock of an underground tunnel. In order to study the influence of joints on the failure characteristics of tunnels, three test schemes with different joint lengths, joint spacing, and joint positions are designed. The results show that the bearing capacity of the tunnel decreases with the increase in the joint length. With the increase in joint spacing, the bearing capacity of the tunnel decreases first and then increases. The crack propagation law of the three test schemes has experienced four stages: no crack, crack initiation, crack rapid development, and crack gradual reduction. The location of joints has the greatest influence on the failure mode of the tunnel. The crack is most likely to appear at the top of the tunnel and expand along the joint, mainly because it is easy to form tensile stress at the top of the tunnel and compressive stress concentration at the joint tip. Therefore, when excavating the tunnel in the underground space, the influence of joints on the tunnel should be considered. Analyzing the relationship between the tunnel and joints has important practical guiding significance for the control of the surrounding rock of the tunnel. Finally, the failure results of the indoor physical model and numerical model are compared and analyzed. They are in good agreement, which also reflects the rationality of numerical simulation.
Highlights
With the development of urban population and economy, the utilization of underground space is increasing day by day, and underground engineering is developing on a large scale
The length of joints has a great influence on the bearing capacity of the tunnel
With the increase in joint length, the failure of the tunnel is mainly concentrated in the joint position at the lower right corner, which is the main reason for the decline of the bearing capacity of the tunnel
Summary
With the development of urban population and economy, the utilization of underground space is increasing day by day, and underground engineering is developing on a large scale. In the underground tunnel research, on the one hand, the deformation and failure of surrounding rock are analyzed by using the theory of Geofluids elastic-plastic mechanics, and the laws of stress and displacement of surrounding rock are studied [6]. It provides a theoretical basis for the support control of surrounding rock. Based on the above research, in this paper, the numerical simulation method is used to systematically study the jointed rock tunnel, three joint distribution schemes are designed, and the effects of different joint distribution forms on the bearing capacity, crack propagation, and failure model of the tunnel are analyzed, respectively. The research content is of great significance for understanding the failure of the tunnel and guiding engineering practice
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