| The working environment is very special in the highway tunnels.Usingan ordinary asphalt pavement structure will produce a lot of smoke and toxic gases in the construction process.These will increase the difficulty of construction technology and environmental pollution.Moreover,there often be a water film on the concrete pavement in long tunnels.Asphalt pavement is prone to damage under the action of water film,and it’s durability will be affected during the late process.In thetunnel,asphalt pavement is easy to cause a fire when it comes to special circumstances.Therefore,most of the pavements in highway tunnel adopt cement concrete pavement structure in our country,and the textures of skid resistance are almost used the groove form.However,there are also many technical problems in the tunnel cement concrete pavement,which is manifested in two aspects: the traffic safety and noise.Many existing cement concrete pavements in accordance with the ordinary cement concrete pavement structure design methods and construction technology.Special requirements of the tunnel environment,structure and materials are not fully considered.No matter whether the three roller shaft construction or the sliding mode construction,the surface layer of the pavement structure will form a thick layer of the lack of aggregate.In addition,the inside of long tunnel are usually very wet,which will cause rapid decay of skid resistance textures,and lead to vehicle slippery and traffic accidents.These issues have become the difficult and urgent problems.The tunnel inside is a relatively closed environment,a travelling vehicle will produce vibration noise,pump noise and aerodynamic noise.These noises propagate in the tunnel through the form of vibration waves,after repeated reflection,resonance and superposition,The propagation of these noises is similar to the horn effect.Which lead to thatthe noise levelin tunnel is much higher than the general section.Psychoacoustic studies have shown that motorists are prone to fatigue when exposed to high levels of noise for long periods of time,adversely affecting the driver’s mental and physical health.In this paper,the skid resistance and noise-reducing requirements of the concrete pavement in highway tunnels are systematically investigated and analyzed.Three kinds of test roads were built in two tunnels,and the properties of skid resistance and noise-reducing effect are deeply studied.The main research contents are as follows:1)The variation ofskidresistance and noise characteristics of the concrete pavement are statistically analyzedinside and outside of the tunnelsby investigating the texture type,texture depth,sideway force coefficient,the skidresistance and noise level.The investigation showed that the skid resistance of the tunnel concrete pavementsis generally inadequate.The skid resistance of tunnel entrance and exit section is the lowest,and thesideway force coefficient of at some section is less than 40.Air humidity has a significant effect on the friction coefficient between the tire and the road surface.The noise level of the concrete pavement inside the tunnel is much higher than that of the ordinary section.The noise level of the asphalt pavement or cement concrete pavement inside of the tunnel is 10 ~ 20 dB(A)higher than the normal section outside of the tunnel,and the noise decay rate is very slow during the tunnel internal propagation.2)Based on the skid forcemodel of Abaqus and noise analysis model of Comsol Multipysics,the skid resistanceof tunnel concrete pavement is studied under the condition of dry,wet,stagnant water and freezing.Both of the transversal and longitudinalacoustic field are studied.The research shows that the skid resistancce of the longitudinal groove is better when the road surface is wet or stagnant.The noise of cross section in the tunnel is mainly distributed around the tunnel and the inner wall of the tunnel.When the distance from the sound source position is equal the noise level is as follows: Transverse groove> Vertical and horizontal groove> Longitudinal groove.The decay rate of sound field is very slow in the longitudinal direction of the tunnel,and the noise level was kept above 70dB(A)at 100 m from the sound field.3)The variation of the skid resistance and the noise characteristics were systematically studied including the groove spacing,the width of the groove,the direction of the groove and the combination modeunder the change of the groove spacing,groove width,groove direction and combination mode The research shows that usingthe longitudinal groove is more conducive to prevent vehicle skidding in the tunnel.The sideway force coefficient of the pavement surface will increase when the groove width is increased and the groove pitch is reduced.The sound pressure in the longitudinal groove is is lower thanthe transverse groove about 4 to 6 dB(A)in the vicinity of the peak area.The noise level increases approximately linearly with the increase of running speed,and decreases with the increase of the groove spacing.4)The variation characteristics of the exposed stone,skid resistance and noise were studied under the influence of aggregate size,gradation type,exposed stone depth,exposed stone area and surface water film.The results show that the maximum nominal particle size of 16 mm has a good effect on the discontinuous grading.The degree of exposure and the area of the exposed stone have significant positive correlation with the sliding resistance and friction coefficient.The skid resistance of exposed stone concrete is less affected by the surface water film.The sound pressure level is decreased with the increase of aggregate size and structure depth.The relationship is the inverse parabola between the exposuredegree and the sound pressure level.That is to say there is an optimum exposed degree of exposed rock concrete,which provides an important basis for controlling the exposed stone effect and the noise level of the exposed concrete pavement.5)The mechanical properties,flexural toughness,skid resistance and noise characteristics are studied under the influence of polymer emulsion,organic fiber and coarse aggregate content.The study shows that the addition of polymer emulsion and organic fiber can effectively improve the mechanical properties and flexural toughness of cement concrete.The flexural tensile ultimate strength is 40% higher than that of ordinary concrete,and the flexural ductility is increased by about 200%,which has excellent resistance to cracking and deformation.Appropriate increase of coarse aggregate quantity is beneficial to the formation of "skeletal dense structure" and macro-texture.When the aggregate content is 45%,the noise level is the least through tire dropping test.6)The TOPSIS multi-objective decision analysis method was introduced in this study.The comfort,skid resistance,noise level and engineering cost are taken into account in order to optimize the "safe,comfortable,quiet,economical" texture type of the tunnel concrete pavement.The analysis shows that the exposed concrete is the best scheme of the tunnel concrete pavement.The longitudinal groove with larger groove spacing(5mm×5mm@25mm)is a reasonable parameter of the tunnel concrete pavement.Transverse combination groove with larger groove spacing gives consideration to the skid resistance and the noise level of the tunnel concrete pavement,which is a reasonable scheme when the structure size is 5mm×5mm@20/40 mm. |
