Study On Deformation And Mechanics Behavior Of Silty Clay Roadbed Under Cyclic Loading And Unloading In Seasonal Frozen Soil Area

In China,the seasonal tundra area is vast,accounting for about half of the national area,and mainly distributed in the north.In the seasonal tundra area,the soil should experience at least one to two freezing-thawing cycles every year.On the one hand,the freeze-thaw cycle effect change the structure of the soil bearing capacity,especially in melts,because there is no completely dissolved,the lower part of subgrade soil in upper subgrade soil drainage is restricted,often the cause of subgrade bearing capacity decreased obviously,and the cause of the mud pumping of roadbed,severe cold injury such as slope sliding phenomenon.Traffic load,on the other hand,is a kind of long-term reciprocating cycle load,the vertical stress cycle changes,especially in the subgrade spring melt,with modern automobile weight increasing,an increasing number of car speed,large load of freight cars such as the frequent use,under the action of cyclic loading caused major damage to roadbed,the highway subgrade sedimentation speeds up unceasingly,also appeared a lot of cracks and dense rut road diseases,such as that the security of the roadbed and operating ability facing a severe test.To explore season frozen subgrade deformation behaviors under cyclic loading and mechanical behavior research,based on the subgrade is melting condition,adopt the world with a frozen soil triaxial apparatus,the season frozen zone is melts the silty clay roadbed under monotonic loading conditions and circulation has carried on the triaxial tests and unloading conditions,which used the grey correlation analysis method,and the different working condition and loading method compares the influence of the strength and deformation of research,research and analysis of the content is as follows:(1)Of the field to retrieve season frozen subgrade soil samples are analyzed in particles,the compaction,the basic physical performance indicators such as liquid plastic limit test,in order to determine the engineering classification of soil,and made a certain degree of compaction in accordance with the requirements of sample,carries on the corresponding test temperature freezing,for related test is melting soil parameters and the research direction.(2)Selecting the including soil samples internal cause and external cause,four kinds of influence factors,on season frozen zone is melting silty clay in the triaxial monotonic loading test,using the gray correlation analysis method of fuzzy mathematics the strength characteristics of the test results for the sensitivity analysis,four factors sensitivity is as sorting: negative temperature > moisture content > melt temperature freezing > confining pressure;The strength increases with the decrease of water content and melting temperature and the increase of confining pressure.The strength increases with the decrease of the negative freezing temperature.After reaching a certain negative freezing temperature(about-10?),the strength increases relatively slowly due to the slow and limited increase of ice crystals.(3)On the samples is melts the silty clay roadbed under different influencing factors of triaxial shear and uninstall cycling test,comparative study and analysis of the three axis loops and unload and under monotonic loading is melt strength and deformation characteristics of soil,indicate found through circulation and uninstall sample will produce a certain plastic damage,strength weakening of the phenomenon.Hysteresis in the process of further research on the circulation and uninstall loopback evolution law of modulus of resilience,hysteresis loop back and according to the modulus of resilience to define the damage variable,reflect is melts the damage of soil,based on hysteresis loop back area defines the dissipation of energy,the damage variable and cycles,dissipation energy and cycle times and damage variable and the evolution of the dissipation can rule.