千枚岩土掺入红黏土微观结构与压缩特性试验研究

Experimental Research on Microstructures and Compression Characteristics of Phyllite Weatherized Soil Blended with Red Clay

千枚岩土和红黏土均为高液限土,不宜直接作为路基填料。为充分利用两种特殊土,通过在千枚岩土中掺入0、20%、40%、60%、80%、100%红黏土配制混合土,研究混合土的液塑限、微观结构与固结试验。试验结果表明:混合土的液限随掺合比的变化规律可以用三次函数表达,当掺合比为13%~52%时混合土的液限低于40%,填料为C组填料,符合该工程基床底层及以下层的应用标准。电镜试验结果表明,千枚岩土颗粒较均匀,红黏土颗粒较小且可以有效地嵌入千枚岩土空隙而改变原有的土的级配,因此混合土干密度较千枚岩土大。固结试验表明,混合土压缩系数随压实度的增加而减小,随红黏土掺合比呈二次函数减小,加入红黏土可以有效降低千枚岩土的压缩性。因此建议碾压方案为红黏土掺入50%,含水率为16%。

Both phyllite weathered soil and red clay are high liquid limit soils,and should not be used as subgrade filling directly.In order to make full use of these two special soils,mixed soils were prepared by adding 0,20%,40%,60%,80%and 100%red clay into phyllite weathered soils.The liquid plastic limit,microstructure and consolidation test of mixed soils were studied.The test results show that the law of liquid limit of mixed soil with mixing ratio can be expressed by cubic function.When the mixing ratio is 13%~52%,the liquid limit of mixed soil is less than 40%.The filler is group C filler,which meets the application standard of the bottom and lower layers of the rail subgrade.The results of TEM test show that the phyllite weathered soil particles are more uniform,the red clay particles are smaller and can be effectively embedded in the phyllite weathered soil voids to change the original soil gradation,so the dry density of mixed soil is higher than that of phyllite weathered soil.Consolidation tests show that the compressibility coefficient of mixed soil decreases with the increase of compaction degree and decreases quadratically with the mixing ratio of red clay.Adding red clay can effectively reduce the compressibility of phyllite weathered soil.Therefore,it is suggested to mix 50%red clay with 16%water content.