浸水条件下石灰改良膨胀土力学性质试验研究

Experimental study on mechanical properties of lime improved expansive soil after immersion

结合特殊路基使用条件,根据室内膨胀土改良及击实试验结果,进行了石灰改良膨胀土浸水不同时间后的直接剪切、固结及CBR(California Bearing ratio)试验,以探索石灰改良膨胀土浸水后力学性质的变化规律,为路堤变形及稳定分析提供计算参数。试验结果表明,浸水后试样表面出现不同程度的松散,导致力学性质指标快速下降,但浸水一段时间后各指标均趋于稳定,其中抗剪强度约为浸水前的70%,压缩模量约为浸水前的30%,CBR强度约为浸水前的80%。分析试验结果,得出石灰改良膨胀土力学性质指标随浸水时间的变化规律,其中,抗剪强度及CBR强度随浸水时间的变化可用对数模型表征,而压缩系数随浸水时间的变化可用乘幂模型表征。应用该研究结果,可以快速预测石灰改良膨胀土浸水后的力学指标,用于路基长期稳定安全分析。

According to special embankment condition, direct shear tests, consolidation tests and CBR tests on lime improved expansive soil after different immersion time were carried out to reveal the changing law of its mechanical property based on indoor expansive soil improvement tests and compaction tests, so as to provide calculation parameters for embankment deformation and stability analysis. The test results indicated that different degree of loose phenomena appeared on the specimen surface after im-mersion, leading to fast falling of mechanical indices;but the indices tended to be stable after a period of immersion time. Com-pared with the samples before immersion, shear strength is about 70%, the compression modulus is about 30%, and the CBR is about 80%. The changing laws of mechanical indices with immersion time are put forward based on analysis of test results, shear strength and CBR reduce with the growth of the immersion time in a logarithmic way while the compression coefficient increases with the growth of the immersion time in a power way. These models can be used to quickly predict the indices of lime improved expansive soil after immersion.