Interfacial stresses of shield tunnel strengthened by a thin plate at inner surface

摘要

For tunnel lining strengthened by bonding thin plate at inner surface, premature failure of interface must be avoided to achieve the desired strengthening effect. Therefore, it is significant and urgent to determine the distribution of interfacial stresses between the thin plate and the tunnel lining. In this paper, an analytical solution for predicting the interfacial stresses was developed based on composite beam theory, and its rationality and accuracy were demonstrated through comparisons with the results of finite element analysis and full-scale experiments. On this basis, the interfacial stresses under various parameters were investigated with the verified solution, e.g., buried depth, elastic modulus and thickness of adhesive layer and thin plate. According to the analytical results, the maximum values of interfacial stresses were predicted to occur at the plate end and decrease rapidly with the distance away from the plate end. When steel plate was used as bonded material compared with Carbon Fiber Reinforced Polymer sheet, the interfacial stresses at the plate ends were much larger at the same tensile strength. Higher adhesive layer thickness caused lower interfacial stresses, while higher elastic modulus of adhesive layer and higher thickness and elastic modulus of thin plate led to higher interfacial stresses. The elastic modulus of the adhesive layer was the dominant factor affecting the interfacial stresses. This research is helpful for understanding the interfacial failure mechanism and promoting anti-de-bonding measures for tunnel lining strengthened by bonding thin plate at inner surface.