Study On Static And Dynamics Of Thawing Silty Clay In Seasonal Freezing Area

Seasonal frozen soil areas mainly exist in the middle and high latitudes of the northern and southern hemispheres.China is the third largest frozen soil country in the world.The frozen soils are widely distributed.In the west of the Helan Mountains to the Ailao Mountains,the north of the Qinling Huaihe Line is vast.The seasonal frozen soils are distributed throughout the region.In the recent years,with the large-scale construction of railways and highways,higher requirements have been placed on the overall stability of the subgrade soil.A series of phenomena such as subgrade soil muddying and mud falling,spring thawing and sinking,etc.,how to take measures to reduce freezing damage has become an important issue for subgrade engineering in the current seasonal frozen area.On the basis of summarizing the current status of research on frozen soil,we find problems and select the critical melting soil as the entry point,and modify the existing instruments in the laboratory to use static triaxial,dynamic three Axis experiments,we use those mesure to explore the influence of different factors on the statics and dynamics of positively fused soils,and analyze them,providing a basis for the construction of subgrade railways and highways in seasonally frozen regions,and contributing to enriching existing frozen soil mechanics The main research includes the following parts:(1)Based on the previous research,we analyzed and found the problem.It was found that the positive thawing soil in the middle state is an important reason for the phenomenon of the subgrade soil.It an important significant research in statics and dynamics.In according with the ?Standards for Geotechnical Test Methods?,physical property tests are performed on selected soil samples,including: particle gradation analysis,liquid-plastic limit test,compaction test,etc.and engineering classification of soil samples,and existing dynamic and static triaxial instruments.It is modified to have the function of unidirectional melting of frozen soil samples to meet the needs of scientific research.(2)Pre-freezing water content,confining pressure,freezing negative temperature,and melting temperature at the top were taken as influencing factors to conduct static triaxial experiments,we explore the influence of different influencing factors on the stress-strain curve and the peak intensity.We make a theoretical analysis to find out that the shape of the curve is different with different factors,and it shows different forms under different water content conditions.Significant analysis of the peak intensity under the influence of the four factors found that the moisture content and confining pressure before freezing were the two most significant factors.(3)According to the results of the static triaxial experiment,the most significant factors were selected for dynamic experiments.We explore the dynamic characteristics under the effects of moisture content before freezing,confining pressure,freezing negative temperature,and melting temperature at the top,and analyzed these factors.The deformation characteristics of the normal melted soil,its curve shape and failure shape are all different from those of the fully melted soil.The damping ratio,rebound modulus,and critical dynamic stress of the normal melted soil under these four factors were investigated.The experimental results are analyzed theoretically.