| In order to prevent the slab damage caused by the inhomogeneous subgrade support in the adjacent area under the slab,it is necessary to define the critical value of soil subgrade treatment degree to ensure the safety of the slab in order to guide the design of engineering parameters and the quality control of construction.In order to explore the influence of the inhomogeneous modulus of subgrade roof on the mechanical properties of pavement slab,based on the finite element analysis software ABAQUS,the effects of the inhomogeneous distribution of subgrade roof and the coupling action of traffic load on the mechanical response of the rigid pavement slab in the airport were analyzed,taking into account the factors such as type and pavement thickness.According to the influence law of inhomogeneous support state of subgrade under the slab,the mechanical properties of rigid slab under different subgrade support conditions were designed and carried out.The strain and load transfer coefficient of rigid slab under different subgrade distribution conditions were obtained,and the variation law of these parameters was analyzed.The results of finite element simulation and experimental study show that the mechanical response and stiffness degradation degree of rigid pavement slab under inhomogeneous subgrade support are affected by various factors,such as type and pavement thickness of pavement slab.Compared with the inhomogeneous subgrade,the bending and tensile stress of the pavement slab increases significantly when the subgrade is not homogeneous supported.For example,when the B737-800 aircraft acts on the veneer,the difference degree of the reaction modulus of the adjacent soil foundation roof increases from 0% to 85.71%,the bending and tensile stress of the pavement slab increases by 34%.The negative influence of non-uniform soil support on the safety of pavement and the service life of pavement can not be ignored.The analysis shows that the critical parameter of the difference degree(β)of the response modulus of adjacent soil foundation roof controlled by different pavement thickness is related to the type,in order to ensure the force safety of the rigid pavement pavement A320 aircraft,The corresponding β of 0.36 m,0.38 m and 0.40 m should not exceed35.5%,59.9% and 70.9%,respectively.When it is B737-800 aircraft,the pavement thickness is not less than 0.36 m,and the corresponding β value of 0.38 m and 0.40 m slab is not higher than 33% and 62%,respectively.When the uneven distribution of soil foundation is considered,the tensile damage factor increases with the increase ofβ,and the tensile damage is obviously higher than the compressive damage.The accuracy of the numerical analysis is verified by the model test of rigid slab supported by inhomogeneous subgrade.It is shown that the difference of the response modulus of adjacent subgrade roof has a significant effect on the mechanical response of slab and the load transfer efficiency at the joint between plates.Therefore,in order to reduce the influence of the uneven distribution of adjacent soil foundation on the pavement structure,the soil foundation leveling and compaction should be done well in the construction stage,or the pavement thickness should be increased appropriately. |
