Research On Structure Of Semi-flexible Of Highway Pavement In Tunnel

Semi-flexible pavement is a kind of advanced pavement,which is filled with Portland cement mortar in open-graded matrix asphalt mixture(the void ratio reaches up to 20%~35%).It has both virtues of ordinary asphalt and cement pavement,and avoids the faults of them.The research and application about semi-flexible pavement is still in the start stage in our country while it has been widely taken into application overseas.Therefore,the study of this pavement has importantpractical significance.First of all,the thesis confirms the mix proportions of matrix asphalt mixture and cement mortar basing on overseas research findings;then,in comparison with ordinary AC-16 asphalt mixture,the semi-flexible pavement shows its excellent road performance by testing.In the paper,the design theory and design methods of semi-flexible compound pavement have been studied mainly.According to the materials which had higher static modulus and larger splitting strength,the relationship between stress and strain and itscracking characteristics and so on,the elastic layered system theory which is the designtheory of asphalt concrete pavement would be selected as the new pavement structure'sdesign theory.In addition,the paper analyzed load stress of semi-flexible compound pavement using ANSYS software,according to variation of each direction of the stress,and gave the response characteristics of load and the locations of the points which wereused in pavement design.The paper analyzed the damage state of semi-flexible compound pavement and indicated that crack was its main failure mode,and then focus on discussing its cracking mechanism,in combination with conventional pavement design method in domestic and overseas,and then put forward design method of the new type of pavement structure,which is that tensile stress as design indicator,the vertical compressive strain of subgrade as checking indicator,and still using double circular vertical uniform load under the theory of multiple layered elastic system to calculate thickness,and then given specific design steps.In addition,the paper discussed its structure combination.Lay the foundation of application of technology of semi-flexible compound pavement in future.