Drainage Characteristics And Structural Combination Design Of Double-layer Drainage Asphalt Pavement

With the development of my country’s road transportation industry,people have put forward higher requirements for the performance of the road surface.Single-layer drainage asphalt pavement is widely used because of its good drainage performance and driving safety.However,the drainage performance of the single-layer drainage asphalt pavement is seriously deteriorated due to the clogging problem during use.The application of the double-layer drainage asphalt pavement can effectively solve such problems.Since there are few studies on double-layer drainage asphalt pavement in my country,it is still in the trial application stage,so it is urgent to carry out research on double-layer drainage asphalt pavement in combination with my country’s geographical environment and climate characteristics.Although double-layer drainage asphalt pavement has strong anti-clogging performance,its drainage performance will still be attenuated under long-term clogging and rutting.Relevant research and evaluation of the road performance of double-layer drainage asphalt pavement are of great significance for promoting the application of double-layer drainage asphalt pavement and improving its drainage performance,driving safety and durability.Firstly,the seepage mechanism of double-drained asphalt pavement is studied by finite element method,and the variation law of internal flow field and water saturation of double-drained asphalt pavement under different pavement structural parameters is analyzed.The research results show that after the double-drained asphalt pavement experiences "primary seepage",the upper layer first reaches the water saturation state;when the "secondary seepage" ends,the lower layer reaches the water-saturated state;the cross slope and upper void ratio of the double-drained asphalt pavement are improved Both the vertical and horizontal penetration rates of the double-layer drainage asphalt pavement can increase the internal void volume of the double-layer drainage asphalt pavement,thereby reducing pore clogging and improving the drainage performance of the double-layer drainage asphalt pavement.Secondly,the application conditions of double-layer drainage asphalt pavement are simulated more realistically by the alternate method of rutting test and clogging test,the water seepage coefficient is measured by the self-developed water seepage meter,and the synergistic effect of rutting and clogging in the process of drainage performance attenuation is studied.The high temperature stability performance of double-layer drainage asphalt pavement was also evaluated.The research results found that with the increase of the "average void ratio",the drainage performance of the double-layer drainage asphalt pavement was enhanced.After the clogging,the upper and lower layers still had a strong drainage capacity when the combination of the upper and lower void ratios was 22%+22% and the thickness combination was 3.5cm+6.5 cm.;The drainage performance attenuation caused by the plug V mixed with different particle sizes is the most serious,the attenuation degree of the water permeability coefficient does not increase with the increase of the particle size of a single plug,the attenuation caused by the plug I is the smallest,and the attenuation caused by the plug II is the largest.;Rutting and clogging often occur at the same time and affect each other,and rutting aggravates the attenuation of the drainage performance of double-layer drainage asphalt pavement;when the temperature is low,under the combination of different void ratios and thicknesses of the upper and lower layers,the clogging in the early stage of the test plays a leading role.Rutting plays a major role in the middle and late stages;when the temperature is high,the pore structure is greatly deformed,resulting in a more significant attenuation of drainage performance caused by rutting.Then,the finite element method was used to analyze the mechanical response and the fatigue life of the double-layer drainage asphalt pavement with different thickness combinations,and the laboratory test was used to study the double-layer drainage asphalt pavement with different amounts of sticky oil(SBS modified emulsified asphalt).The optimal amount of viscous layer oil is determined,and the critical rainfall intensity of different pavement structural parameter combinations is determined by the multiphase flow and porous media coupling model,and the optimal structure that meets the engineering meteorological conditions is proposed.Parameter combination design scheme.The research results show that the mechanical response of the double-layer drainage asphalt pavement with different thickness combinations has a small difference,and they all meet the requirements of the specification.The void ratio has a greater impact on the drainage performance,and the lower layer void ratio has a smaller impact;when designing the combination of the double-layer drainage asphalt pavement structure,it needs to be determined based on the local pavement pollution level and meteorological conditions.When the annual rainfall is large and the intensity is high when the road surface cross slope and the upper layer void volume are appropriately increased,when the road pollution level is heavy,the upper layer void volume should be appropriately reduced and the upper layer thickness should be increased.Finally,the pavement performance of double-layer drainage asphalt pavement was evaluated by laboratory test,and the high temperature stability performance,low temperature crack resistance performance and water stability performance were evaluated by rutting test,low temperature trabecular bending test and freeze-thaw splitting test respectively.At the same time,the function recovery of the completely clogged double-layer drainage asphalt pavement is carried out through the two maintenance methods of first flushing and then suctioning and first suctioning and then flushing,and its drainage performance is improved.The test results show that the double-layer drainage asphalt pavement designed in this thesis has good road performance,and its drainage performance has good recoverability.After the double-layer drainage asphalt pavement is clogged,the maintenance method of first suction and then flushing can better restore its drainage performance.