Study On Strength And Cumulative Deformation Of Runway Foundation In Permafrost Region

The wideness of the airport runway,the large and concentrated load,make its roadbed temperature and stress distribution significantly different from ordinary roads.According to the mid-and long-term plans for airport construction,airport construction will continue to be carried out in permafrost regions in the future.Therefore,in view of the engineering characteristics of airport runways,carrying out research on the strength and cumulative deformation of airport runway pavement in permafrost regions has important practical significance for the design and safety assessment of airport runways in permafrost regions.For this reason,this paper takes the permafrost region in Northeast China as the research object,and through numerical simulation,theoretical analysis,indoor testing and other methods,under the comprehensive consideration of the coupling of water,heat,and force,a comparative analysis of the runway and the frozen soil of the highway and railway is carried out.The stress distribution and deformation characteristics in the foundation,and the evaluation method of the strength of the runway pavement under the action of aircraft load and the cumulative deformation are studied to provide a theoretical basis for the construction of airport runways in permafrost regions in China.The specific research contents and results are as follows:1.Based on the two-dimensional finite element model of the runway in the northeast permafrost region,the distribution law of the temperature field and the temperature stress of the roadbed in 30 years are analyzed.Further on the basis of the roadbed temperature field,combined with the dynamic characteristics of the aircraft,the dynamic characteristics of the roadbed structure under the action of the B737-800 representative model are analyzed,and compared with the road and railway roadbeds under the load of cars and trains.The study compares the vertical additional stress and displacement distribution of the roadbed of the three road structures under the two conditions of the freezing period and the spring melting period.2.The influence depth of additional stress under the different aircraft load,soil foundation rebound modulus and temperature were analyzed by finite element method.Furthermore,the relationship between the temperature of the roadbed,the reaction modulus of the soil and the modulus of resilience within the depth of influence of the roadbed was analyzed,and the law of the reaction modulus of the soil within the depth of influence of the roadbed with temperature was obtained.3.Based on indoor low temperature frozen soil dynamic triaxial test,the simulation in permafrost regions airport runway based on force and deformation characteristics of aircraft loads,study the initial moisture content and confining pressure,loading frequency,loading frequency,the axial dynamic stress amplitude,loading time interval,and considering the effect of freeze-thaw cycles on the accumulation of frozen silty clay deformation,the influence law of dynamic modulus of elasticity.4.A calculation method and model for the cumulative deformation of permafrost roadbed under aircraft load are proposed.An airport runway in a cold region is taken as an example to analyze the cumulative deformation,and then based on the results of the deformation,suggestions for foundation treatment are proposed.