Mechanical performance of ultra-high performance concrete (UHPC) prefabricated arch reinforcement in highway tunnels

Ultra-high performance concrete (UHPC), characterized by its remarkable attributes of high strength and exceptional toughness, demonstrates significant potential for application in tunnel reinforcement. This study proposes a UHPC prefabricated arch lining reinforcement method featuring segmental installation and direct bolt connection. Taking a three—lane highway tunnel as the research prototype, systematic numerical simulations are carried out to comprehensively compare and analyze the failure modes, stiffness degradation patterns, and load—bearing capacities of UHPC prefabricated arch linings and cast—in—place RC integral arch linings. Results show UHPC arch linings achieve approximately 77.6% higher load-bearing capacity compared to conventional RC arch linings. Under combined vertical loading V = 600 kPa and horizontal loading H = 120 kPa, the UHPC lining demonstrates about 30% reduction in damaged area but 15–18% greater settlement values. Moreover, UHPC arch linings show a 15—30% higher load—sharing ratio than RC counterparts, with significant differences in load—sharing ratios observed at various sections of the arch linings.