Study On Structural Durability Of Sponge City Permeable Asphalt Pavement In Northern Area

This paper studies the durability and applicability of the fully permeable asphalt pavement structure in the northern region.The research content of this paper is mainly divided into three parts:(1)Designing the structure of the fully permeable asphalt pavement according to the existing research results combined with the rainfall conditions in Beijing;Different water permeable materials are selected for different structural layers of the fully permeable asphalt pavement:the permeable surface layer material is selected from the permeable asphalt mixture,and the permeable base material is selected from the porous graded crushed stone,the long and short cement stabilized macadam,and the long and short cement concrete;(2)Conducting indoor raw material performance testing and mix design,and conducting freeze-thaw cycle tests on permeable asphalt mixture and long-space cement stabilized macadam material to simulate the frost resistance of two water permeable materials in winter in northern China;(3)According to the designed fully permeable asphalt pavement structure and grading paving test road,150,000 accelerated loading tests were carried out using ALF equipment to study the durability and applicable performance of different structures.Through the study of these three aspects in turn,the paper draws the following conclusions:(1)This paper selected three fully permeable asphalt pavement structures and a semi-permeable asphalt pavement structure through structural design;(2)It can be found that the freeze-thaw cycle test in the two states has little effect on the water seepage performance by setting the freeze resistance of the multi-space cement stabilized macadam material in the water-immersed freeze-thaw group and the wet-frozen group.Its mechanical properties have a greater impact:the compressive strength of the water-immersed freeze-thaw specimens is reduced by 15.09%compared with the compressive strength of the wet-frozen specimens,while the splitting strength is relatively reduced by 28.57%;The relationship between the mass loss of the test piece and the decrease of the mechanical properties was studied.It is believed that the mass loss caused by the continuous peeling of the surface of the test piece after the freeze-thaw cycle is an important cause of the decrease of the mechanical properties.(3)After 150,000 accelerated loading tests,data on rutting depth,road surface deflection,and roadbed settlement of four structures were obtained.Depth of rutting of four structures:C structure>B structure>D structure>A structure;road surface deflection value:C structure>B structure>D structure>A structure;subgrade settlement:B structure>C structure>A structure>D structure.Through the rutting and deflection data,it shows that the A structure has the best bearing capacity,the D structure is the second,and the C structure is the worst.The subgrade settlement data can be considered as:the gravel soil subgrade is better than the lime soil subgrade and the silt subgrade.A permeable gravel roadbed is used for permeable pavement construction and a filter geotextile is placed between the roadbed and the basement.(4)Through the accelerated loading test,it can be concluded that the bearing capacity of the semi-permeable structure is better than that of the fully permeable structure,and the bearing capacity of the A structure in the full permeable structure is the best.It can be recommended that the road load capacity is strong.The A structure and the D structure are used for the non-mixed road surface and the parking lot pavement,while the B structure and the C structure can be recommended for light-duty roads such as sidewalks,square pavements,and internal roads.