Structural Implementation Method of Yielding Support for Deep Tunnel in Weak Rock

In order to make the yielding support scientifically applied in deformation control of deep tunnel in weak rock, the conventional support mode which mainly based on bending deformation yielding is changed, and the structural implementation approaches of yielding support is studied based on the theory of structural stability and large deformation mechanics. The conclusions can be listed as follows: (1) the stability of surrounding rock is analyzed with the arch structure as basic mechanical model, the integral and systematic control measures should be taken; (2) the influence of geometric nonlinearity should be reduced in the initial support, so as to realize the yielding demand of deforming largely, and avoid the occurrence of large deformation mechanical effect; (3) in the leveling process of variable stiffness " rigid-soft-rigid" of the initial support, it must be based on the premise that the bearing capacity and stability are guaranteed; (4) the key to the formation of composite structure between surrounding rock and primary support is the matching degree of mechanical properties and the shear resistance of contact surface.