Study On The Long-term Deformation Characteristics Of The Frozen Soil Foundation Under The Dynamic Load Of The Aircraft

According to the requirements of the 13 th Five-Year Planning and Development of Civil Aviation Administration of China,China will gradually carry out airport construction in the frozen soil areas in Heilongjiang.The engineering construction in the permafrost region is a global problem.Under the background of global warming,the long-term stability of the airport is more prominent.The essence of long-term runway stability in permafrost environment is the long-term cumulative deformation of the frozen soil subgrade under the combined effect of aircraft load and environmental factors.Based on this situation,in this paper,based on the indoor low-temperature dynamic triaxial test and numerical simulation,the dynamic deformation of permafrost subgrade under plane load,the deformation characteristics of frozen-thaw soil in Heilongjiang China and the permanent deformation of subgrade under long-term aircraft loading are studied,the main research contents and achievements are as follows:1,The finite element software was used to construct the temperature-stress field based on the surface temperature monitoring in Heilongjiang and the dynamic load coefficient suitable for the aircraft.The variation law of the dynamic stress amplitude of the soil under different ambient temperature and pavement structure was studied.2,Based on the triaxial test of undrained low temperature and based on the dynamic test of freeze-thaw silty clay under long-term cyclic loading,the effects of water content,confining pressure,frequency and frequency of freeze-thaw cycles on the dynamic plastic deformation of subgrade soil are studied,the permanent plastic deformation law of frozen soil under the long-term action of aircraft load was obtained.And by the matlab software,the cumulative plastic strain model was fitted through the test results.3,Based on the cumulative plastic strain model of newly constructed permafrost and thawing soil,five types of factors including aircraft type,rolling speed,level of field flatness,replacement depth of soil foundation,and freezing and thawing state of soil foundation were considered.The accumulated strain law generated by the road base of a district under aircraft loads.The damage degree of the subsoil under the irregular dynamic stress wave is expressed by the damage model,which provides convenience for the evaluation and monitoring of the settlement in the flight area during the operation of the airport.4,On the basis of global warming of permafrost degradation,establishment of long-term deformation prediction model for field bases based on comprehensive effects of power and ambient temperature.Study the long-term stability of airports in the permafrost region under global warming conditions and the airport foundation's long-term deformation with increasing temperature.