Research On The Frost Heaving Sensibility And Classification Of Highway Subgrade Coarse-grained Soil In Seasonally Frozen Ground Region

With the rapid growth of economy, the request of developinghighway is increasing. Freeway has a more and more effect ondeveloping economy. The seasonally frozen ground region is widelydistributed in our county, and it spreads more than 10 provinces andcities of the north of the Changjiang River. For this reason, in thenorth, frost damage of highway subgrade in seasonally frozen groundregion is always a puzzle of local highway construction. The freewaywhich is built in frozen regions not only cannot exert its convenienceand high speed ,but also increases the problem of security whenfreeway is used usually , cause lose in life and property and addto the maintenance cost of the frosten damage road due to the subgradefrost damage including pavement of uneven bulge , flexible pavement's crack , rigid pavement's break and frost boiling in spring .So,to study the fundamental principle of freeway subgrade frost damageand to explore the law according to that it takes place and developis becoming more and more important. For these reasons, the paperrespectively studies frost heaving of silty sand, fine sand , mediumsand and coarse sand with the different of clay content , watercontent , dry density , degree of saturation. And then we do thelaboratory research on coarse-grained soil frost heaving sensitivity,comprehensively analysis the factors that influence the frostheaving susceptibility of coarse-grained soil of freeway, givereasonable advice to frost heaving susceptibility classification ofcoarse-grained soil according to the result of laboratory frostheaving test of coarse-grained soil . The text consists of eightchapters.The first chapter introduces the aim and significance of thefrost heaving susceptibility of highway subgrade coarse-grained soilin seasonally frozen ground region, the study trends of the soil frostheaving susceptibility and classification, the device condition oflaboratory frost heaving test and preparing work before test.The second chapter introduces the research on frost heavingsusceptibility of silty sand. The regression analysis of siltysand(5#) of ηand w, ηand Sr, ηand γ d are set up and give relevantregression formulas. The relevance and contribution rate analysiscan conclude that water content, dry density and saturation have aremarkable effect on frost heaving sensibility, especially watercontent.The third chapter is focused on lab research on frost heaving offine sand , which is divided into two groups by claycontent ,multi-clay fine sand(6#) , little clay fine sand(11#), theregression analysis and relations of ηand w, ηand Sr, ηand γ dare set up by means of statistics and given regression formulas.The relevance and contribution rate analysis can conclude that watercontent, dry density and saturation have a remarkable effect on frostheaving sensibility, especially water content. The effect ofsaturation on frost heaving becomes weak when clay content increases.By contrast analysis, there is no significant difference of frostheaving about C=13.5% and C=7%.It is unsuitable conclusion that C=10%is a susceptibility limit specified by standard.The fourth chapter is discussed the lab research on frost heavingof medium sand , which is divided into five groups by clay content(C=5,10,15,20,25%),the regression analysis on relations of ηand w,ηand Sr, ηand γ d are set up by means of statistics and givencorrection regression formulas. The relevance and contribution rateanalysis can conclude that water content, dry density and saturationhave a remarkable effect on frost heaving sensibility, especiallywater content. The effect of saturation on frost heaving becomes weakwhen clay content increases. By means of numerical analysis ofstatistics and t method, it is not raised that water content of 15%is susceptibility limit of medium sand.The fifth chapter is discussed the lab research on frost heavingof coarse sand , which is divided into three groups by clay content(C=10,15,20%),the regression analysis relations of ηand w, ηandSr, ηand γ d are set up by means of statistics and given correctionregression formulas. The relevance and contribution rate analysiscan conclude that water content, dry density and saturation have aremarkable effect on frost heaving sensibility, especially watercontent. The effect of saturation on frost heaving becomes weak whenclay content increases. By means of numerical analysis of statisticsand t method, it is not raised that the clay content of 15% issusceptibility limit of coarse sand.The sixth chapter is introduced aim, significance and presentstatus of frost heaving susceptibility classification. Frost heavingclassification of silty sand, fine sand, medium sand, coarse sand,and etc is raised, and contrast with standard, the difference of twois explained, and then the paper gives a new classificationrevisions.The seventh chapter discusses the laboratory research on siltysand, fine sand, medium sand, coarse sand, and so on. Mainly by meansof t method and Q-model cluster analysis verifies that both frostheaving and (w-w0) can be comprehensively analyzed and researched onrelevant frost heaving. At the same time, we discuss and researchon w0 ,and use the basic physical quality of soil to express it, andgain the remarkable effect. The frost heaving experience formulagained from the test have more universal significance.The eighth chapter is the conclusion of the paper. The aboveresearch on frost heaving of coarse grained soil can conclude frostheaving regularity and the limits of frost heaving classification.