The Research On Construction Technology Of Large Thickness And Semi-Rigid Base Of Trunk Highway

The construction of trunk highway has not been paid enough attention compared with the rapid development of expressway network that has been basically built.With the toll cancelled,the number of vehicles on the trunk road is increasing exponentially,which makes traffic more and more crowded.Therefore,trunk roads cause a large number of diseases for such frequent traffic loads and traffic flows.The base is the main bearing layer of asphalt pavement,and its strength determines the service life of the pavement.At present,the semi-rigid base that mainly adopts layered construction process,which is difficult to ensure the overall stress of the structure layer.Therefore,the stress and strain of the bottom of the whole semi-rigid base are large,and the strength is difficult to meet the design requirements,is difficult to meet the design requirements for strength,resulting in the base be easily destroyed during service.With the development of large equipment,the one-off construction plan of semi-rigid base will be a new direction,and how to ensure the successful implementation of the one-off construction will be the focus of the research.Based on the Traffic Science and Technology Project "Hunan province trunk highway overhaul and durability technology research" of Hunan province,a new technology of one-time construction for large thickness semi-rigid base that adapted in the Trunk road repair has completed a series of studies in this paper.The main research content is as follows:First,taking the disease of National provincial trunk highway of Hunan as the breakthrough point,the causes of the disease were investigated through the core drilling inspection for base,and the main reasons were analyzed:The strength and interlayer bonding state of semi-rigid base is one of the main causes.Finite element BISAR3.0 software is used to analyze the stress condition under different bonding states of base.Results show that the main reason for the sudden change of stress is the incomplete continuous bond between base layers.The stress at the bottom and bottom of the base is the smallest in a completely continuous state.It show that the one-step construction of large thickness semi-rigid base has the strongest resistance to fatigue failure,and the force is more reasonable.Secondly,the high quality gradation is the key to forming a semi-rigid base with large thickness.Base on the filling theory and combining the mineral material interference theory,the mixture ratio design of semi-rigid base is completed by filling vibration test and the control range of key sieve hole passing rate is put forward through the analysis of the structure type of semi-rigid base material and cement stabilized macadam.Finally,the control range of the large thickness Cement stabilized macadam base ratio design is verified through the one-time construction test section of cement stabilized macadam base with a thickness of 36cm.The improvement measures are put forward based on the analysis of the construction problems occurring in the test section,and then the quality test shows that the effect is significant.The observation at the later stage of the test section shows that the pavement is in good condition,indicating that this technology has good application prospects.At the same time,it is proved that the control range of the key sieve hole pass rate of the large thickness semi-rigid base is reasonable and the key control points of construction are correct.It can be used as the technical guidance for the one-time construction of semi-rigid base with large thickness.