Crack Propagation Mechanism And Crack Resistance Of Carbon Geogrid On Asphalt Pavement

Based on the typical asphalt pavement structure in the North China Plain of Hebei Province,this thesis studies the propagation mechanism of reflective cracks in asphalt pavement under different environmental loads through theoretical analysis,numerical simulation,laboratory experiments and other methods,analyzes the mechanical behavior and crack propagation mode of the prevention and treatment of reflective cracks by gegrates,and proposes the development of a new type of carbon fiber gegrates for the prevention and treatment of reflective cracks.Some problems related to the prevention and treatment of reflection cracks with new carbon fiber geogrid is investigated.The main conclusions are as follows:(1)Studying the propagation mechanism of reflective cracks in asphalt pavement under vehicle load.Based on the theory of fracture mechanics,the load field model of typical semi-rigid base asphalt pavement was established by extended finite element method.The stress field distribution of asphalt pavement under vehicle load and the influence of driving speed and load state on the propagation of reflective cracks were analyzed.The results showed that the reflective crack of asphalt pavement had both open and shear propagation trends under vehicle load,and the propagation mode was compound.Reducing traffic speed and vehicle load could inhibit the spread of reflective cracks on asphalt pavement.The reflection cracks spread upward in a straight line form and further spread in a curved path after reaching the surface layer.(2)Studying the development and evolution law of pavement reflection cracks under the joint action of temperature and vehicle load.By establishing the finite element model of asphalt temperature field,the temperature field changes of asphalt pavement structure layer in different seasons were analyzed.Then combined with the temperature field model,the coupling effect model of asphalt pavement temperature and vehicle load was established,and the reflection crack propagation mode of asphalt pavement under the joint action of temperature and load was analyzed.It is found that the open propagation mode of reflective cracks in asphalt pavement was mainly affected by temperature,while the shear propagation mode is mainly affected by vehicle load.Under the action of temperature and vehicle load in summer and autumn,only shear reflection cracks appear on asphalt pavement.In winter,under the action of temperature and vehicle load,not only open reflection cracks but also shear reflection cracks appear on asphalt pavement,and the trend of open reflection cracks is mainly.(3)Studying the reflection crack propagation law of geogrid-reinforced asphalt pavement.The effect of geogrid on the reflection crack is analyzed by laying geogrid on asphalt layer in the form of thin film.The results show that the geogrid can effectively reduce the propagation trend of open and shear cracks.The higher the geogrid modulus is,the better the anti-cracking effect is,and the larger the crack propagation Angle is.(4)Experimental study on mechanical properties of carbon fiber geogrids and interlayer bonding property of reinforced asphalt.The effects of tensile method,tensile rate and longitudinal rib stiffness on the tensile strength of transverse rib of carbon fiber geogrid were analyzed through laboratory tensile tests.It was found that carbon fiber geogrid was a kind of material with high tensile strength,low elongation and brittle failure,and have good mechanical stability.Through direct shear tests and oblique shear tests,the influence of carbon fiber geogrid laid in asphalt surface layer on its interlayer bonding property was studied,the influence of different longitudinal ribs of the geogrid on shear strength,shear displacement,shear stiffness was analyzed,and the internal friction Angle of two kinds of carbon fiber geogrid laid in different surface layers was obtained based on Moerculen theory.(5)Experimental study on cracking and fatigue resistance of carbon fiber geogrid-reinforced asphalt.The low temperature cracking resistance of two kinds of carbon fiber geogrid reinforced asphalt layer was analyzed by trabecular bending test.The results show that both kinds of carbon fiber geogrids can improve the low temperature cracking resistance of asphalt surface layer,inhibit the upward development of cracks,and reduce the crack opening degree.The fatigue resistance of asphalt layer reinforced with carbon fiber geogrids was studied by four point bending test.The results show that the fatigue resistance of pavement can be effectively improved by laying carbon fiber geogrids in asphalt layer.