Failure behavior and reinforcing design of degraded tunnel linings based on the three-dimensional numerical evaluation

Abstract

Void diseases behind the lining can commonly occur in tunnel structures. In this research, the failure behavior and reinforcing design of degraded tunnel linings with double void diseases were investigated. The effect of void disease on the three-dimensional distribution of inner force was explored. Subsequently, the stress distribution and plastic failure behavior of degraded tunnel linings with void diseases were studied. Then, the reinforcing behavior of the fiber-reinforced plastic (FRP)-polymer cement mortar (PCM) method was concerned. Finally, the distribution of potential cracking zone was discussed. The main results in this research indicated that the three-dimensional distribution of bending moment is greatly affected by the voids behind the lining, and the lining exhibits obvious bending outwards phenomenon within the void-affected zone. Concerning the failure characteristics between the double voids, plastic shear failure is prone to occur at the outer surface, but tensile-shear failure is likely to generate at the inner surface. In addition, the failure rate can be significantly affected by the spatial distribution of voids. Furthermore, the FRP-PCM method can significantly reduce the failure rate of the tunnel linings. Moreover, the distribution of potential cracking zone including the tensile cracking zone (TCZ), shear cracking zone (SCZ), and tensile-shear cracking zone (TSCZ) was determined.