Study On Anti-cracking Tecnnology Of Asphalt Pavement In Seasonal Frozen Area

In the seasonal frozen area,the environmental temperature varies greatly.Under the action of temperature and load,the asphalt pavement is prone to reflect cracks and other diseases.Investigating the asphalt pavement disease in the northern Shanxi frozen area and starting from the design of mechanical index,the finite element simulation and experimental research is applied to analyze the structure form of the semi flexible base asphalt pavement,and a new idea for prevention and control of reflective cracks in seasonal frozen area was put forward..Firstly,the main road disease is reflected as reflection crack by the field investigation and disease analysis of the road in the northern Shanxi frozen area,and its formation mechanism is analyzed,and the common prevention and control measures of the reflected crack disease are summarized.In order to avoid the expansion of reflective cracks at the grassroots level,a semi flexible base was proposed by comparing and analyzing the advantages and disadvantages of semi-rigid base and flexible base.Combined with the survey data,the structural form of semi-rigid base,flexible base and semi flexible base asphalt pavement is obtained by HPDS design and checking calculation.By analyzing the influence of temperature and load on the road,the coupled model of temperature and load of asphalt pavement in seasonal frozen area was built by the Abaqus software,Based on which,the stress intensity factors at the crack tip of three kinds of base was calculated and analyzed,and the reflection crack of semi flexible base in the seasonal frozen area is more stable.Secondly,a mechanical index system was established,by the analysis of mechanics indexes in highway asphalt pavement design specification and combining the characteristics of seasonal frozen area.Using the grey relational entropy method and taking the stress intensity factor as the evaluation object,the mechanical index sequence of the anti reflective crack performance of the asphalt pavement was obtained.Reflective cracking effect of semi flexible base asphalt pavement presents a better anti reflective cracking effect by contrasting the mechanical indexes of semi-rigid base,flexible base and semi flexible asphalt pavement,and using the entropy weight-TOPSIS method.Thirdly,the mechanism and other properties of the strength formation of the semiflexible base was explored by the analysis of the interaction of cement and emulsified asphalt in the semi flexible base mixture,and the mechanical test,such as the unconfined compression strength,the modulus of compression resilience and the indirect tensile strength of the semi flexible base mixture,as well as the dry shrinkage test and the freezing thawing test,were tested.The good performance of semi flexible base mixture was obtained.Finally,based on actual project implementation,the construction technology of semi flexible base was summed up.The life cycle cost analysis of semi flexible base asphalt pavement was carried out by present value method,and its good economic benefit was obtained,which provides guidance for the use of semi flexible base asphalt pavement.The application of this result can reduce the generation of reflective cracks,improve the service life of roads,reflect the design concept of energy conservation and emission reduction,and has broad application prospects.