Numerical Study on the Mechanical Behavior of Shotcrete Lining with Yielding Support in Large Deformation Tunnel

The yielding support has proven to be one of the most effective measures to control the large deformation of the tunnel, as it could well stabilize tunnel support structure by releasing the deformation energy in the surrounding rock and exerting the self-supporting ability of the surrounding rock. To explore the damage mechanical behavior of shotcrete linings with yielding supports in large-deformation tunnels, an elastic–plastic damage model of concrete was developed, and a numerical method for simulating the yielding support based on the double-node beam element and interface element was proposed. Then, the influences of the position and resistance of the yielding element on the behaviors of shotcrete lining were analyzed and discussed. The results indicate that the position and resistance of the yielding element have a significant effect on the distribution of damage, principal stress, axial force, and bending moment of the lining. In the tunnel dominated by horizontal deformation, the yielding structure with constant resistance symmetrically arranged at the waist of the tunnel sidewall has the best yielding effect. The damage and maximum axial force are minimal, and the maximum bending moment is relatively large but lower than the maximum bending moment that the lining structure can bear. Assuming that the yielding element position stays the same, the maximum lining axial force rises with increasing yielding resistance, the maximum bending moment shows an initially upward and subsequently downward trend as the yielding resistance rises, and the maximum damage shows a trend of first declining and then growing as the yielding resistance rises. It is also found that the resistance of the yielding component should be controlled within a reasonable range, neither too small nor too large, for the lining to be in good working condition.