Research On Pavement Structure Scheme Of Pohe Tunnel In Guangxi Jing-Na Highway

In recent years, the construction of highway is booming and developing in the Mid west China—a mountainous place where tunnels have been widely used. Therefore, we should give full considerations for these crucial factors including the selection of an appropriate pavement structure, the method for prolonging the pavement's service life and the issue associated with the improvement of pavement's operational performance.Three forms of rigid pavement have been adopted for tunnel constructions: the concrete pavement, though being with advantages involving high bearing strength, long service life,perfect thermal stability and good riding visibility, these structures are considered as defective and imperfect yet so that numerous problems can be found in the construction of tunnel.There still exist many joints for concrete pavement and the skid resistance of the surface of rigid pavement decreases rapidly. The asphalt pavement have advantages of smooth surface,low traffic noise, maintenance convenience and short term of hindering the traffic. Once fire and water damage occur in tunnel, the asphalt pavement may aggravate these disasters in a potential way. And the rigid-flexible composite pavement is regarded as a structure with driving comfort, high integral strength and long service life. And it costs lower than continuously reinforced concrete and asphalt concrete pavement, also has disadvantages, for instance, the reflective cracking can be normally found in the asphalt overlay at the joints Based on the Pohe tunnel of Guangxi Jing-Na highway, this research will provide three pavement forms for tunnel design purposes.First, based on the existing pavement scheme of Pohe tunnel in Guangxi Jing-Na highway, analyzed the effect of temperature field in tunnel, end structure processing of composite pavement, the anti-slide and noise reduction and other factors in tunnel. With reference to the relevant specification and documents, a new pavement structure scheme was put forward, mainly including the thickness of asphalt surface layer of import and export, the thickness of continuously reinforced concrete, reinforcement design, determination of anti sliding and noise reduction measures of cement concrete pavement in tunnel.Secondly, the interlayer shear strength was used as design index, then design the composite tunnel pavement structure by the method of segmented design. The tunnel pavement structure was regarded as an elastic layered system by BISAR3.0 to calculate,including the interlayer maximum longitudinal shear stress and the maximum shear stress under different thickness of asphalt layer and cement slab. According to the situation ofserious overloading in China, the variation rule of maximum shear stress under different axle load conditions was analzyed, and a composite tunnel pavement scheme which is reasonable and economy was put forward.Finally, in order to solve the problems of application of asphalt pavement in tunnel, such as poor construction condition, dark light Pavement structure scheme which use continuously reinforced concrete pavement in whole tunnel was presented.Focused on the difference of environment conditions between tunnel import and export and the central of tunnel, the main consideration of continuously reinforced concrete pavement structure are maximum temperature difference and humidity inside the tunnel. Calculated reasonable reinforcement ratio of Pohe tunnel pavement in two parts, verified the feasibility of using different reinforcement ratio in tunnel with different positions, pointed out some key points of continuously reinforced concrete pavement construction in tunnel. Results of this study can provide basis for design of tunnel pavement structure, and it has a certain reference and application value.