喷射高韧性混凝土加固拱结构的力学性能试验研究

Experimental study on mechanical performance of arch structures strengthened with sprayed high ductile concrete

针对公路隧道混凝土二次衬砌的裂缝控制问题,设计制作了二次衬砌的拱结构缩尺模型,并分别在内表面喷射10 mm厚高韧性混凝土薄层、粘贴碳纤维布及二者组合的方法进行了加固。通过静力加载试验,对不同加固方式对拱结构承载力、径向变形、钢筋应变、破坏模式等力学性能进行了研究。结果表明:喷射10 mm高韧性混凝土将隧道二次衬砌拱结构的破坏模式由压剪破坏变为受压破坏,其起裂荷载、屈服荷载和极限荷载分别提高了13.6%、68.9%和29.9%,同时,初裂后刚度提升了63%,有效控制了拱结构的径向变形,提升了公路隧道二次衬砌在运营期的整体受力性能;而在相同受力条件下,粘贴碳纤维布的加固方法对拱结构的承载力及径向变形并没有起到明显的改善效果。

Aiming at the crack control problem on the concrete secondary lining of highway tunnel,the arch structure scaled model of the secondary lining was designed and made.The inner surface of the tunnel was reinforced by spraying a 10 mm thickness layer of high ductile concrete,sticking carbon fiber sheet and the combination of these two methods.Through the static loading tests,the mechanical properties of different reinforcement methods on the bearing capacity,radial deformation,reinforcement strain and failure mode of the arch structure were studied.The results showed that the failure mode of tunnel secondary lining arch structure is changed from compression shear failure to compression failure by spraying 10 mm high ductile concrete.The initial crack load,yield load and ultimate load are increased by 13.6%,68.9%and 29.9%respectively.Meanwhile,the stiffness after initial crack is increased by 63%,which effectively controls the radial deformation of the arch structure.It improves the overall mechanical performance of the secondary lining of highway tunnel during the operation period.However,under the same stress condition,the reinforcement method of sticking CFRP has no obvious effect on the bearing capacity and radial deformation of the arch structure.