The Experiment Research On Frost Heaving Susceptibility Of Coarse-grained Soil Of Expressway Subgrade In Northeast Seasonally Frozen Ground Region

As an important and necessary basic facility,the highway presents the irreplaceable function and status not only in transportation and economic construction but also in production and living.With the development of economy,the request of developing highway is also increasing.Highway construction has become a necessary work for developing the national economy and promoting social progress.The area of seasonal frozen ground is more than half of the whole country in China,therefore,the primary problem of highway construction in northern region is the frost heaving of subgrade in seasonal frozen area.For the highway in seasonal frozen area,because of the annual freezing and thawing of subgrade soil,because ofthe annual freezing and thawing in subgrade soil,subgrade frost damage often displays as uneven uplift of the road surface,cracking of the road surface or even melting sinking and road tumbling,which greatly affects the normal use of roads and also increases the number of roadsmaintenance costs.Therefore,studying on the influencing factors of subgrade frost damage andexploring the development law of roadbed frost damageso as to prevent and control the roadbed frost damage.Wedo the Lab research on frost heavinglaw of silt,fine sand,medium sand,coarse sand and fine gravel soil with different influencing factors such as clay content and saturation.This paper mainly consists of six chapters.The first chapter introduces the distribution of frozen soil in China,the significance of research on frost heaving of subgrade soil in seasonally frozen region and the current research status of frozen soil heaving in and out of our country.The last one is the main work and technical route of this paper.In the second chapter,the basic principles of frost heaving in the frozen area were briefly summarized first.Then introduced the test program and test equipment for the indoor frost heaving test and the test results were sorted out after the tests.The third chapter isthe analysis of the frost heaving test results ofcoarse-grainedsoil.Respectively using the factors of water content,dry density,saturation,and clay content for regression analysis of the frost heaving rate of coarse-grained soils and significant test to obtain the law that how each of these factors Influence on the frost heave rate of coarse-grained soils.The fourth chapter is a comprehensive analysis of coarse grained soil test data with the aid of data analysis software SPSS.Considering the three factors of water content,clay content and particle size of coarse-grained soil for setting up a multiple regression equation to evaluate and predict the frost heave rate.The fifth chapter is to classify thefrost swell coarse-grained soils according to the analysis of the previous parts,comparison and analysis of frost heaving classification ofindoor test and standard classificationand through the difference from the standard to improve the freeze-thaw rate evaluation model.The sixth chapter is recommendations and conclusions of this article.Through the analysis of the frost-swelling test of coarse-grained soil and several factors affecting the frost heave rate of coarse-grained soil,we obtain the changing rule of the freezing-increase rate by the influence of various influencing factors and the equation for evaluating the frost heave rate by comprehensive factors.To expect that has practical reference significance to the project.