| Highway tunnels become structurally deficient during use for various reasons. Besides, due to aging, degrading of the structural materials, improper uses and the lack of maintenance, the safety, adaptability and durability of tunnel structures has been rendered inadequate. In this case, CFRP, which has such incomparable advantages as high tensile strength, light weight, resistance to corrosion, high durability and ease of installation, would an effective method worthy applying in the rehabilitation of tunnels. For the mechanical behaviors of CFRP strengthened tunnel lining exert a fundamental effect on the calculation method of CFRP strengthened highway tunnels, the dissertation makes a theoretical study on debonding failure, section bearing capacity, crack and deformation of RC eccentrically-loaded member, and develops a reasonable calculation method that applies to the use of CFRP in highway tunnels. The contents are mainly summarized as follow:1. According to the present research data on the debonding failure of RC flexural members reinforced with CFRP, the stress status of bonding area and the mechanism of debonding failure for CFRP strengthened tunnel lining are analyzed, and the mathematical criterion of bonding failure is put forward. Combined with the main factors that induce the bonding failure, the corresponding engineering measurements are proposed.2. Corresponding to the four failure modes of CFRP strengthened RC eccentrically-loaded member, under second load, the entire process analysis method that calculates the stress of lining section and the ultimate limit state method that calculates the ultimate bearing capacity are put forward. N-M curves and practical case show that CFRP can effectively strengthen the tunnels that tension failure occurs on the inner part of the lining.3. Based on the crack and deformation theory of RC eccentrically-loaded member, the formulas that calculate the crack resistance, crack width and flexural stiffness are proposed. Through a practical case, the rules that the crack and deformation of the tunnel lining varies with the increase of the load and the reductionvalues of flexural stiffness corresponding to different loading phases are given.4. Base on the load-structure method, the method that analyzes the internal force of the lining structure with cracks is proposed, the section strength verity formulas for the tunnel lining reinforced with CFRP are summarized, and a reasonable calculation method that applies to the use of CFRP in highway tunnels is primarily formed. Besides, the application condition for CFRP strengthened highway tunnel is given.In sum, CFRP can effectively reinforce the cracked tunnel lining and improve the status of tunnel structure to some extent. The study on the calculation method of CFRP strengthened highway tunnel lining provides a reference for the use of CFRP in the rehabilitation of highway tunnels, and impels its application in the field. |
