Study On The New Anti-freezing Expansion Technology For Subgrade Filling Of High-speed Railway In Severe Cold Area

This paper mainly focuses on the new improved method of anti freezing expansion test.The main research work includes:(1)The research development status of soil and summarizes the deficiency of cement and lime improved soil in frozen heaving.Through market research choose 3 typical model modifier.Unconfined compressive strength test to judge the performance of selected.Modified an agent for anti freezing expansion effect is good.(2)The silt and silty clay as the modified object.Using A type modifier and cement as modifiers.To carry out 3 kinds of ratio of compaction test,each group was repeated 6 times.30 times the frost heave test of freeze-thaw cycle of unconfined compressive strength test.Durability test and permeability test.Analysis of saturated freeze-thaw cycle variation regularity and intensity of frost heaving deformation under subgrade filler.(3)According to the test results,evaluation of modified silty sand The feasibility of using silty clay as anti freezing expanding filler and the suggestion of using A modified agent are given.The main results and conclusions are as follows:(1)The basic physical characteristics of typical silty sand,silty clay and its improved soil were obtained,and the fillers,amendments and mechanism were analyzed and compared.(2)The frost heave test and unconfined compressive strength test results are as follows: the effect of cement specimens with freeze-thaw cycles increases the frost heave upward trend with cement added,no increased first and then decreased compressive strength,strength loss,weight loss rate,poor durability.(3)The frost heave test and unconfined compressive strength test effect of A modified agent is as follows: adding A modified specimen with freeze-thaw cycles increases frost heave and maintain a stable growth of non minimal agents,are after the first growth to maintain a stable trend of compressive strength,and the ratio of mixed with cement to improve the 20~50%,strength loss rate and mass loss rate than the cement,good durability in cement.(4)The application of A composite modifier in high speed railway is suggested: 5%~8%A modified agent is added into silty sand,and 15%A modified agent is added into silty clay as an anti freezing expansion method.(5)The frost heaving rate is the main control index of frost heaving resistance,and the unconfined compressive strength under freeze-thaw cycles is the index to evaluate the durability.