Study On Asphalt Pavement Structure Of Highway Tunnel Based On Full Scale Experiment

In recent years,with the rapid development of China’s infrastructure industry,China has become a transportation power,tunnel power.However,the research on the tunnel has been limited to its own structure and fire prevention lighting during operation,while the research on the road surface in the tunnel is rare.As a result,the road surface design in the tunnel can only apply experience or copy the general section design specifications outside the tunnel.However,the tunnel is very special,with differences in stress and space closure.Therefore,it is very important to study the inter discipline of road and tunnel in the field of tunnel pavement.The cement pavement in the tunnel has been used for many years,and the technology is relatively mature.Under the general trend of "white to black",the use of asphalt pavement in the tunnel has been put forward gradually.At present,a large part of the tunnel pavement under construction or renovation has adopted the rigid base asphalt pavement based on concrete,while the semi-rigid base asphalt pavement outside the tunnel is the main pavement in China.In order to better connect the inside and outside of the tunnel,the semi-rigid base asphalt pavement inside the tunnel is also considered.In addition,considering the high overall strength in the tunnel and the good control effect of the flexible pavement on cracks,the asphalt pavement with flexible base is also worth exploring.This text in transportation science and technology projects in Zhejiang province "Changchun to Shenzhen expressway(G25)building heart to Jinhua,Zhejiang section of the tunnel engineering based on the full scale test pavement structure optimization research" the background,the first of the tunnel in different asphalt pavement in numerical calculation,the innovative will consider in tunnel surrounding rock grade,puts forward the surface of the key factors affecting road tunnel.On this basis,the optimal pavement design was carried out for paving the experimental section of fulllength acceleration loading in the tunnel,and the mechanical behavior of different asphalt pavement in the loading process was explored.The main research contents and results are as follows:(1)Through numerical calculation,it is pointed out that the cement concrete base reinforcement of the rigid base asphalt pavement in the tunnel is not good,and the low grade(C30 is enough)plain concrete without bottom base can be used as the base,focusing on the influence of the thickness of the asphalt surface layer.(2)For semi-rigid base asphalt pavement,the base is under pressure,the base fatigue cracking is not considered;The key influencing factors are the thickness of asphalt surface layer and base layer.The shear stress decreases first and then increases with the base layer thickening.The relation between the permanent deformation and the thickness of asphalt pavement is linear.(3)When flexible base asphalt pavement is used in the tunnel,the strength of surrounding rock is unfavorable to the stress on the bottom of the asphalt layer and the top of the roadbed;The key factor is the thickness of the asphalt layer.As the amount of permanent deformation of the flexible pavement is relatively large,the thickness of the asphalt layer should be controlled reasonably instead of being too thick.(4)Through the full-size accelerated loading experiment in the tunnel,the service status of different asphalt pavement used in the tunnel was analyzed,and the results showed that: the rigid base asphalt pavement can be treated with thinness asphalt surface layer,and the low-grade plain concrete is used as the base The strain response in the loading process is similar,which can be promoted from the technical and economic point of view.(5)Due to the high strength of bedrock in the tunnel,the use of flexible base asphalt pavement does not affect the overall strength of the road surface The bearing capacity of rigid base asphalt pavement decreases with the loading times In the long run,the flexible asphalt pavement will be in better service in the tunnel.