Abstract: The primary support structure of the tunnel would be damaged due to soft rock deformation under high ground stress. Therefore, the yielding technology of surrounding rock is investigated and the yielding joint to relieve support displacement and reduce surrounding rock pressure is proposed. The influence of bolt preload and groove shape on the working performance of yielding joint is analyzed based on finite element simulation and a 1∶1 prototype joint axial loading test. The analytical results show the following. First, the joint deformation pressure can be released according to setting mode, and the resistance to deformation is stable. Second, the preload and groove shape significantly affect yielding joint; the greater the preload and the narrower the groove, the higher the sliding resistance. Finally, the type of diameter shrinkage groove consumes huge energy, with a high safety reserve. Therefore, the yielding joint can release surrounding rock energy and provide stable resistance during the working process.

Key words: squeezing surrounding rock, tunnel, yielding technology, yielding joint, yielding support, groove, preload