Theory And Application Of Optimization Design Of Rural Highway Surface Structure With Small Traffic Volume

Rural road with small traffic volume is an important part of road construction,as well as an important link of modern rural construction.Due to the different natural conditions and economic development in different regions,the structure form of rural road surface with small traffic volume in natural villages lacks reference and pertinence,and there is no relevant standard guidance.At present,the Ministry of Transport of China has issued the Technical Standard for Rural Highway Engineering with Small Traffic Volume(JTG-2111-2019)to guide the highway design of administrative villages,but there is still a lack of corresponding standard guidance for the road structure design of connecting lines in natural villages.This paper plans to launch a research on the different combinations of cement concrete pavement structures and different thickness of cement concrete pavement structure layers of small traffic rural roads that meet the use requirements,so as to minimize the traffic investment cost of natural rural roads on the basis of ensuring the normal service life of small traffic rural roads,the limited funds in more rural road construction.Based on the above situation,the research work in this paper mainly includes several aspects:(1)The traffic volume and road damage forms of rural roads with small traffic volume in natural villages in henan province were investigated on the spot,and the standard axle load of rural roads with small traffic volume in natural villages in henan province was put forward through the analysis of the traffic volume,representative models and axle load of the field investigation.According to the investigation and analysis:The axle load of rural roads with small traffic volume in Henan Province is basically less than 60kN.For small traffic roads,the pavement thickness should not be calculated according to the standard axle load BZZ-100.Therefore,according to the axle load analysis,it is determined that the axle load of rural roads with small traffic volume in Henan Province is basically less than 60kN.The standard axle load of rural roads with small traffic volume in Henan is set as BZZ-50 single axle and single wheel group.(2)According to henan province,the natural conditions such as topography and climate,through the scene of the soil base resilience modulus of region of henan province experimental investigation,combined with the existing various areas of henan province in the small traffic volume of rural highway pavement thickness design of soil base resilience modulus value,summed up the small regions of henan province rural highway traffic soil base resilience modulus.The calculation and analysis show that when the elastic modulus of soil foundation is 30MPa and the plate length is 3m,the minimum surface layer and the thickness of base layer are 16cm in mountainous area.When the modulus of soil foundation is 40～60MPa,the minimum thickness of surface layer and base layer is 15 cm.When the modulus of soil foundation is between 70 and 80MPa,the minimum thickness of surface layer and base layer is 14cm.In the mountainous area,when the plate length is 2m and the soil rebound modulus is 30-40MPa,the minimum thickness of surface layer and base layer is 14cm.When the modulus of soil foundation is between 50 and 80MPa,the minimum thickness of surface layer and base layer is 13cm.In the plain area,when the length of the plate is 3m and the elastic modulus of the soil foundation is 30-50MPa,the thickness of the minimum surface layer and the base layer is 16cm.When the modulus of soil foundation is 60～80MPa,the thickness of the minimum surface layer and base layer is 15cm.In the plain area,when the plate length is 2m and the rebound modulus of soil foundation is 30MPa,the minimum thickness of surface layer and base layer is 15cm.When the modulus of soil foundation is 40～70MPa,the minimum thickness of surface layer and base layer is 14cm.When the modulus of soil foundation is 80MPa,the minimum thickness of surface layer and base layer is 13 cm.(3)Based on the theoretical calculation and finite element simulation analysis of the traffic volume,the thickness of pavement structure,the design years and the elastic modulus of soil foundation in different areas of henan province,the pavement structure thickness of rural roads with small traffic volume in different areas of henan province is determined.Taking the soil modulus of 40MPa as an example,the load fatigue stress and temperature fatigue stress of different plane size and plate thickness are analyzed and discussed,and the comprehensive fatigue stress of pavement is calculated.According to the principle that the comprehensive fatigue stress of pavement should not be greater than the standard bending tensile strength value of cement concrete 4.0MPa,The reasonable minimum plate thickness is determined when the design axle load is BZZ-50 with single axle and single wheel group.The plate length in mountainous area is 3m,2m,and the minimum plate thickness is 15cm,14cm.Plain area plate length 3m,2m,minimum plate thickness 16cm,14cm.