增湿-冻融劣化原状黄土结构强度试验研究

黄土结构强度是由内部颗粒的空间构型而产生的一种胶结性的联结强度。该强度极易受外界环境的扰动,如增湿、冻融等,引起体积和孔隙变化,削弱黄土的结构强度,进而又会影响路堤、边坡、护栏等黄土构筑物的稳定性。本文选取陕西临潼Q_3原状黄土为研究对象。首先,通过室内模拟增湿和冻融循环作用,分析不同含水率和冻融循环次数下黄土的体积和孔隙的变化规律。其次,通过侧限压缩试验数据绘制出含水率和冻融循环次的关系曲线,并得出黄土在增湿和冻融情况下的压缩变形特征。最后,依据该关系曲线定义黄土结构强度、剩余结构强度,和劣化因子等概念,采用数理统计方法拟合出三者之间的数值表达式,并应用本试验数据计算出所有工程作业对黄土的扰动劣化值,从而得出在增湿和冻融作用下的原状黄土结构强度的劣化规律。

Structural Strength Deterioration Test Characteristics of Undisturbed Loess by Moistening and Freezing-thawing

Loess structural strength is a cemented joint strength that is self-generated by the spatial configuration of the soil particles inside the loess, and its size is highly susceptible to disturbance by the external environment. Common external environmental disturbances, such as moistening and freezing-thawing cycles, which cause volume and pore changes that have an important impact on the structural strength of the loess. These changes in turn affect the stability of structures such as embankments, slopes and guards. In this paper, the test samples were selected from Lintong Q₃ undisturbed loess. Firstly, by simulating the action environment of moistening and freezing-thawing cycling in laboratory, the variation law of loess sample volume and pore were analyzed with the increase of water content and with the increase of freezing-thawing cycles under different water content. Secondly, the e-lgp compression curves of loess are drawn through the lateral compression test data with increasing water content and with increasing freezing-thawing cycles under different water content, and the compression deformation characteristics of loess were analyzed under moistening and freezing-thawing cycling. Finally, the concepts of structural strength, residual structural strength and deterioration factor of loess are defined according to the e-lgp compression curve, and numerical equations for structural strength, residual structural strength and degradation factor of loess are fitted by mathematical statistics. The disturbance deterioration value of loess working before the test is calculated by using the confined compression test data, and the deterioration law of the structural strength and deterioration factor of undisturbed loess are analyzed under the action of moistening and freezing-thawing cycles.