Research On The Construction Technique Of Flyash Subgrade

With the development of the national economy, expressway of our country is increasing quickly. Specific character of high-grade highway is high fill, which needs a great deal of filling material. The use of flyash as filling material of subgrade can reduce filling material from agricultural soil, which is a good idea solving the competition soil material with ground. Because flyash belongs to the light quality material, it can be used effectively as filling material of subgrade on soft ground, having a important function to the stability of embankment. So using flyash as filling material of embankment, it is focused on engineering field extensively. It is the main path that turns flyash from discard for the treasure. If it can be reasonably exploited, it will produce the good economic performance and social performances.Flyash has characteristics of light self weight, high intension, small compression and rapid consolidation, which is very benefit to improve the stability of embankment. But flyash is also defect of small cohesion and large capillarity, which is a bad affection to increase stability of embankment. In addition, if content of heavy metal of flyash exceeds standard, it will be harm to environment. At present, design specification and job specification about flyash embankment still have no to be formed idealized system, so it can't guide construction in large scale engineering completely. It is necessary to test and research on actually engineering, abacus on design, construction, experiment and detection on flyash embankment etc., then a more reasonable technique project is put forward, providing abundant construction experience and theory companion to highway engineering constructor.Based on construction of Lian-Xu expressway, construction technique of flyash subgrade is discussed detail in this paper.Through carrying on laboratory test of raw material, testing in trial pavement section, analyzing and summarizing test data and so on, admixture project of flyash and lime about main line and bridge head section is put forward, construction technique parameter such as lay-down coefficient, compaction thickness, combination of roller machines, number of roller passes is obtained. At the same time, analysis about affection of meteoric water on flyash embankment is make, attention event of flyash embankment construction is build to guide to flyash embankment construction of Lian-Xu expressway', and to provide the useful engineering technique data for the application of flyash embankment construction technique in our country.