工程包边法路堤填芯弱膨胀土的含水率变化常处于特定区间,现行研究集中于浸水饱和状态下的膨胀量,对特定含水率变化区间膨胀土的膨胀变形量研究较少。为研究不同增湿量下弱膨胀土土体的膨胀变形特性,采用“等同”的重塑膨胀土试样进行不同增湿量的一维膨胀试验,结果显示,当土体的含水率达到25%时,继续增大含水率对于土体膨胀变形量的影响较小。基于此,提出了换算膨胀量的概念(换算线膨胀率、换算膨胀力),通过对路堤内部施工含水率及平衡含水率进行分析,结合增湿变形量的研究结论,得出用于路堤内部的含水率变化处于对膨胀变形量影响较大的区间,路堤填筑时需严格控制土体的施工含水率。

The water content of weak expansive soil used in subgrade constructed with wrapping method usually varies in a certain interval. Current researches are focused on expansive amount under saturated status rather than that under certain intervals of water content. To investigate the expansive deformation of weak expansive soil with different moistening degrees,one-dimensional expansion test was conducted on “equivalent” remolded expansive soils moistened to different water contents. The “equivalent” here means the same soil type with identical initial moisture content and dry density. Results showed that when water content reached 25%, further increasing the water content has little impact on the expansive deformation. On this basis,the concept of converted expansion (converted linear expansive ratio and converted swelling force) is put forward, which is defined as the difference between the linear expansion of original specimen moistened until saturation and the linear expansion of original specimen moistened until any random water content.Through analyzing the construction water content and equilibrium water content inside the subgrade, the interval of water content inside subgrade which remarkably affects expansive deformation amount was obtained. It is concluded that the construction water content shall be controlled strictly in embankment filling.