戈壁粗粒土填料填筑铁路路基压实评价指标研究

选取兰新铁路第二双线4个具有代表性的路基试验段,进行戈壁粗粒土填筑路基的压实质量评价指标研究。研究表明:粗粒土填料填筑路基的孔隙率偏小,但现有规范规定的孔隙率标准偏大,起不到控制路基密实度的作用,因此提出用填料的细颗粒室内击实试验得到的孔隙率换算整体孔隙率的方法控制粗粒土填筑路基的密实度;K30能较好地反映填料的塑性变形,且对压实质量敏感,比Ev2更适合作为路基压实质量的评价指标;Ev2/Ev1控制路基压实质量的实质是Ev1在起作用;规范不应用统一的Ev2/Ev1标准,而应根据填料的粗颗粒含量制定相应的Ev2/Ev1标准,填料的粗颗粒含量越多,填筑的路基的弹性变形量越小,Ev2/Ev1的规范标准应越大;Ev1的测试深度比K30大,且塑性变形在总变形中的比例也大,因此可以考虑将Ev1设定为路基压实质量的评价指标。

Study on the Assessment Indexes of Compaction Quality for Railway Subgrade Constructed by Gobi Coarse-Grained Soil Filler

Four representative subgrade test sections on the second double-track of Lanzhou-Xinjiang Railway were chosen to carry through study on the assessment indexes of compaction quality for railway subgrade constructed by Gobi coarse-grained soil filler.Results show that the porosity of railway subgrade constructed by the coarse-grained soil filler is small.However,the value of the porosity standard in the existing criteria is greater,which can not control subgrade density.Accordingly,such method that through the porosity obtained from indoor compaction test of the fine particles to convert the whole porosity is proposed to control subgrade density.K30 can properly reflect the plastic deformation of the filler and is sensitive to the compaction quality,so K30 is more suitable than Ev2 as the assessment index of compaction quality for railway subgrade.Ev2/Ev1 is used to control the compaction quality of subgrade,Ev1 is functioning essentially.The uniform value of Ev2/Ev1 in the existing criteria is improper.Corresponding Ev2/Ev1 standard should be worked out according to the content of coarse particles.The more content of coarse particles,the less elastic deformation of the filled subgrade,and Ev2/Ev1 standard should be greater.The testing depth of Ev1 is greater than that of K30,and the plastic deformation constitutes a high proportion of the total deformation.Therefore,Ev1 may be considered as the assessment index of compaction quality for railway subgrade.