Discussion on the Application of Yielding Support Technology for Large Deformation of Soft-Rock Tunnel

Abstract

A new method for traffic tunnels with large deformations of soft rock is produced based on the research and development of a new yielding anchor and on the successful application of a large deformation tunnel to a coal mine system. Moreover, this new method should adopt the basic principle of timely support, strong support, and yieldable support to maintain a certain supporting resistance to preserve the stability of surrounding rocks and somehow allow displacement for the support system. Therefore, the support system’s functions include supporting, yielding, and unloading. A yielding support system can then be designed according to the basic principle, comprising of parts such as yielding anchor, sprayed concrete, pressure controller, and arch frame. Combinations of the yielding system components and key technical problems for future resolution are proposed by discussing the basic yielding anchor mechanism and analyzing the components of the system and these problems. The main technical problems include deformation coordination and yielding support system stability; determining the relationship and amount of free surrounding rock deformation; surrounding rock and support joint deformations, and constant resistance yielding; setting the initial yielding load scientifically; and maintenance of the constant resistance characteristic of the components. Meanwhile, field test research on the yielding support system should be combined with a suitable project background to further verify the suitability and reliability of the system.