Study on the Effect of Yielding Support and Energy Characteristics of Surrounding Rock in Deep Soft Rock Tunnel

As an effective measure to solve the cracking problem of primary support in large deformation tunnels, yielding support has an important influence on the mechanical properties of primary support and the energy characteristics of the surrounding rock. Based on the stress-strain curves of common yielding members, the mechanical characteristics of yielding members are summarized, and a numerical method is developed to realize the mechanical properties of yielding members based on the Beam element and Interface element. The concrete elastoplastic damage constitutive model is used to carry out numerical calculation, and the influence of yield member position and its constant resistance on the mechanical properties of the initial support and surrounding rock energy is discussed. The results indicate that: It is beneficial to reduce the internal force and damage of spray layer and the stress and energy of surrounding rock by setting compression members in different positions, and when the maximum initial geostress is oriented horizontally, the pressure-relief effect of yield members subjected to horizontal deformation is more pronounced. When the yield member position is fixed and the constant resistance is different, the maximum damage of spray layer, bending moment and axial force all increase first and then decrease with the increase of constant resistance, and the rock stress and elastic strain energy density around the hole also increase first and then decrease with the increase of constant resistance.