Abstract:

The large squeezing deformation of soft rock can not be ignored under the rapid development of tunnel construction. As a result, yielding anchor bolt becomes more and more important in large deformation control. The structure and support mechanism of a new type of yielding anchor bolt with large allowable deformation are introduced. And then the performances of the anchor bolt during elastic deformation phase, sliding yielding phase and tensile phase are verified by ANSYS software. Finally the yielding pressure and yielding deformation of the anchor bolt are analyzed by probit analysis based on Hoek formula and ABAQUS software respectively. The results show that: 1) The lower limit exists in yielding pressure of the anchor bolt; and the higher the compressive strength of rock mass is, the smaller the lower limit of anchor bolt is. 2) The decreasing amplitude of secondary lining decreases when the yielding deformation of anchor bolt reaches a certain value. The concept of “supporting while yielding and flexible support goes first and then rigid support” can be realized; large deformation of surrounding rocks can be controlled effectively; and the longterm stability of the tunnel can be improved during the tensile phase of yielding anchor bolt with large allowable deformation.

Key words: yielding anchor bolt with large allowable deformation, large deformation of soft rock, Hoek formula, yielding pressure, yielding deformation