冻融循环下水泥改性膨胀土物理力学特性研究

Physico-mechanical Properties of Cement-modified Expansive Soil under Freeze-thaw Cycles

为探究冻融循环作用对水泥改性膨胀土物理力学特性的影响,以南阳膨胀土为试验对象,进行不同掺灰比的水泥改性,然后对经历不同冻融循环次数后的试样进行变形测量和无侧限压缩试验。试验结果表明:在冻融循环过程中,水泥改性膨胀土试样的含水率损失量较小,不同掺灰比试样的体积变化规律均呈现为"冻缩融胀",掺灰比越大,试样体积的变化幅度越小,最大冻缩量和最大融胀量也越小,但会存在一个最优水泥掺灰比。冻融循环作用对水泥改性膨胀土力学特性的影响较大,尤其是初次冻融。随着冻融循环次数的增多,不同掺灰比试样的强度与弹性模量逐渐降低并趋于稳定,掺灰比越大,强度和弹性模量的衰减量越小。水泥改性膨胀土经历冻融后韧性变好。

In the aim of exploring the effect of freeze-thaw cycles on the physico-mechanical properties of cementmodified expansive soil,Nanyang expansive soil which was modified with cement in different mixed ratios was selected as test objective,and then deformation measurements and unconfined compressive test were carried out after different freeze-thaw cycles. Results showed that the water loss of cement-modified expansive soil samples was little in the process of freeze-thaw cycles. The pattern of volume change of samples with different cement dosages could be all described as＂shrinking in frost and expanding in thaw＂.The bigger the cement ratio was,the less the variation of volume change was,and the smaller the maximum frozen shrinkage and maximum thaw expansion were.Yet there was an optimum cement ratio.Freeze-thaw cycles had a great effect on the mechanical properties of cement-modified expansive soil,especially for the initial freeze-thaw cycle.With the increasing of freeze-thaw cycles,strength and elastic modulus of samples with different cement ratios decreased gradually and then tended to be stable.The larger the cement ratio was,the smaller the attenuation of strength and elastic modulus were.The toughness of cement-modified expansive soil improved after freeze-thaw cycles.