Research On Shear Resistance Of CRC+AC Composite Pavement Based On Strain Energy Theory

With the continuous development of Chinese economy,the highway construction has experienced high-speed stage for nearly twenty years.The increasing traffic volume and traffic load leads to the emergence of new features of transportation,such as heavy axle load,multi axle and high tires pressure.The traditional asphalt concrete pavement and cement concrete pavement have undergone a lot of diseases under the current traffic conditions.Therefore,it is necessary to study the pavement structure with higher service level,and the CRC+AC composite pavement is a new type of high performance pavement structure.The asphalt surface provides a good running function,and the continuous reinforced concrete slab is mainly responsible for load-bearing in the CRC+AC composite pavement.Due to the difference in material properties between the asphalt layer and the concrete slab,the inter-layer is a place where some diseases like slip,deformation and cracking could appear.At present,there are some limitations in the study of inter-layer shear resistance,and the traditional shear strength method which does not take the second principal stress into consideration has some defects.This paper proposes the study and analysis about shear resistance based on strain energy theory,and uses the strain energy index to determine the shear state of composite pavement.Firstly,the three-dimensional finite element model of composite asphalt pavement on continuous reinforced concrete base is established by using finite element software,the strain energy and horizontal shear stress of asphalt concrete layer and inter-layer are calculated,and the connection and difference between the two indexes are analyzed.The results show that under the combined action of vertical load and horizontal load,the maximum value of strain energy appears in the upper part of the asphalt surface layer.The strain energy concentration zone of the road surface is behind the load area along with the horizontal load direction.Although the inter-layer strain energy is slightly smaller,the inter-layer strain energy admissible value may be insufficient.The most unfavorable region of strain energy and the worst area of horizontal shear stress in the inter-layer show consistency,and the most unfavorable points between the layers are in the front of the load area along with the horizontal load direction,which initially confirms the reliability of the index of strain energy.Then the paper studies the influences of some factors on the strain energy by taking the most dangerous point as the feature point.The results show the strain energy is sensitive to the changes of thickness and elastic modulus of the asphalt surface,and the increase of both factors can result in the decrease of strain energy.The thickness and the reinforcement ratio of concrete slab have little effect on the magnitude of inter-layer strain energy,however,both of them play an important role in preventing the destruction of concrete slab.Reasonable reinforcement can take good control of spacing of transverse cracks,not only protect the concrete slab but also have a positive effect on reducing the inter-layer strain energy.In the case of overload,the strain energy ascends significantly,and the condition of high temperature and overload is terrible to inter-layer.The inter-layer bonding state has little effect on the strain energy,but it can affect the shear stress.At this time,it is difficult to determine the inter-layer shear state using the shear stress index,which proves the limitation of shear stress index.