Experiment Study On The Frost-heaving Properties Of Cement Stabilized Crushed Stone Subgrade

As a nation abundant in frozen soil,seasonal frozen soil regions accounted for 53.5% of the total territory of the nation.With the vicissitudes of seasons, frost heavingand thawing in subgrade of seasonal frozen soil can occur repeatedly and as aconsequence lead to uneven frostand thawing settlement,posinggreat threats to railway traffic.In this paper,we take high-speed railway subgrade in seasonal frozen soil area for the research background,analyzing the influence factors of subgrade frost heaving,the graded broken stone was determined as the research object,Changing gradation composition to be done as the research method.By applying the frost-heaving and thawing-settlementapparatus,many tests of graded broken stone andcement stabilized crushed stonehave been carried out,such asfreezing and thawing test,unconfined compressive strength test, unconfined compression test. The main research contents and achievements are as follows.(1)Accordingto the testrequirement,authorhasdeveloped a frost-heaving and thawing-settlementapparatus,the test apparatus and the device’s work performance is good, they can satisfy the user’s demand.(2)Through the freezing and thawing test of graded broken stone andcement stabilized crushed stone,this paper carried outtestresearchon temperature field, temperature gradient, freezing depth, water content, frost heave, thaw settlement. The main results show that the temperature curve of the sample presents cosine trend,the frost heave is larger than thethaw settlement in general,the gradation and cement content are the key factors effecting the frost heave rate of the cement stabilized crushed stone.With the increase of the cement content or decrease of fine content the frost heaving ratio decreased.(3)By experimenting the penetration test and unconfined compressive strength test,the close relationship among permeability coefficient,compressive strength,fine content,cement content has been identified,the gradation which complys with specifications was determined through the two controlling parameter.(4)Take the frost heave ratio, permeability coefficient, compressive strength into consideration comprehensively,the most appropriate gradation for high-speed railway subgrade in seasonal frozen soil regions was singled out.