为解决高地压、高流变条件下软岩隧道围岩及支护结构大变形控制难题，通过理论和数值分析，研究让压预应力锚索在隧道大变形控制中的作用机制。研究内容包括2个方面，一是研究新型让压锚垫板在低预紧力及低围压下的力学性能，满足支护结构先柔让压的要求； 二是让压结束后，预应力锚索在高预紧力条件下改善支护结构受力性能，实现后刚强支的作用。结果表明： 1）预应力锚索通过施加预紧力，增大洞壁径向阻力，提高围岩稳定性； 2）预应力锚索在让压结束后对支护结构的主要作用是减跨，由此提高支护结构刚度和承载能力； 3）围岩、支护结构和让压预应力锚索变形协调，力学上相互耦合，构成“先柔后刚”的支护体系。

The control of large deformation of surrounding rock and supporting structure of soft rock tunnel with high geostress and high rheology conditions is very important. Hence, the action mechanism of prestressed yielding anchor cable in large deformation control of the tunnel is studied through theoretical and numerical analysis. The study includes two aspects as follows: one is the study on mechanical properties of new type of yielding anchor plate under low pretightening force and low surrounding rock pressure to meet the requirements of flexible support; the other one is the study on the stress bearing performance of supporting structure improved by prestressed anchor cable under high pretension condition after yielding pressure to realize the function of rigid support. The study results show that: (1) The prestressed anchor cable can increase the radial resistance of tunnel wall and improve the stability of surrounding rock by applying pretension force. (2) The main effect of prestressed anchor cable on supporting structure after yielding pressure is to reduce the span, thus to improve the stiffness and bearing capacity of supporting structure. (3) The deformation of surrounding rock, initial support structure and prestressed yielding anchor cable is coordinated and mechanically coupled to form "soft first and hard afterwards" support system.