含砂低液限粉土路基压实标准的探讨

Study on compaction standard of subgrade with bearing sand silt of low liquid limit

通过含砂低液限粉土物理性能、标准击实和固结压缩的室内试验研究 ,分析了其压实特性 ,得出了结论 :该类土的击实曲线离饱和曲线较远 ,说明土的孔隙中空气体积较大 ,土并未达到真正的密实 ,按现行的压实度指标控制压实 ,标准偏低 ;黄河冲积形成的低液限粉土 ,其粉粒含量高 ,粒径比较均匀 ,粘土颗粒含量极少 ,塑性指数低 ,砂粒和粉粒之间的空隙没有更多的细小粘粒来填充 ,这是造成粉土难以压实的内在原因 ;压实度K =90 %时 ,孔隙比e>0 .7,土处于疏松状态 ,说明该压实度区存在较大的压缩性 ,应取消 90 %压实度区 ;提出了以空气体积率作为该类土的压实控制标准 。

According to the study on experiments indoors of bearing sand silt of low liquid limit, including physical characteristics, the standard compaction and compression tests, the compaction property of silt is analyzed and several conclusions can be drawn: The distance between the compaction curve and the saturation curve is far, which approves the volume of air in void is high, the real density of silt can not be got, and the compaction standard is lower based on the current compaction degree for controlling construction; Yellow River alluvial silt has distinctive character: the content of silt grains is fairly high, the particle size is quite uniform, the content of clay grains is very poor, the plasticity index is low, and there are fewer fine clay grains filling the void between sand and silt particles, which is the main reason for difficult compaction through conventional construction technology; As the compaction degree K=90%, the ratio of void e>0.7, which means the density is low and the compressibility is high, so zone 90 should be cancelled; The volume ratio of air used for controlling compaction standard is put forward and some reasonable causes are given in this paper.