延安新区黄土压缩特性试验研究

Experimental research on compression characteristics of loess in Yan’an New Area

为研究高填方体黄土在侧限压缩状态下的结构性变化及其变形特性,以延安新区某场地黄土为研究对象,开展原状、重塑黄土的高压固结试验,研究不同试验条件下原状、重塑黄土的压缩特性及结构性变化规律,探明黄土的初始结构性、结构屈服压力与压缩指数之间的关系,考虑黄土结构性参数建立了修正的黄土一维压缩模型,并结合试验结果进行了验证。试验结果表明:增减湿和压实度的变化直接影响黄土的初始结构性和压缩特性,含水率的增大导致结构屈服压力和初始结构性的减小及压缩指数的增大,初始结构性参数与结构屈服压力及压缩指数均呈线性变化关系;重塑黄土的压缩变形随压实度的增大而减小,压缩指数随结构屈服压力和初始结构性的增大而减小;在同一含水率下,原状黄土的初始结构性参数明显大于重塑黄土;在增湿作用下原状黄土初始结构性的削弱程度远大于重塑黄土的削弱程度;采用结构屈服压力和压缩指标表征了原状黄土和重塑黄土之间的初始结构性参数关系函数,计算模型显示,随着压实度的增大,含水率的变化对黄土压缩指数和初始结构性的影响逐渐减小,而对结构屈服压力的影响仍较为显著。

In order to study the structural change and deformation characteristics of high fill loess under lateral compression,taking the loess of a construction site in Yan’an New Area as the research object,the high-pressure consolidation test of undisturbed and remolded loess was carried out to study the compression characteristics and structural change law of undisturbed and remolded loess under different test conditions.Then the relationship between initial structure,structural yield pressure and compression index were investigated,based on which a modified one-dimensional compression model of loess was established,which was then verified by the test results.The test results show that the changes of moisture and compactness directly affect the initial structure and compression characteristics of the loess,the increase of water content is accompanied by the decrease of structural yield pressure and initial structure,and the increase of compression index.The initial structural parameters change linearly with the structural yield pressure and compression index.With the increase of the compactness,the compression deformation and compression index of the remolded loess decrease,whereas the structural yield pressure and initial structure increase.Under the same moisture content,the initial structural parameters of the undisturbed loess are significantly higher than those of the remolded loess,and the weakening ability of the initial structure of undisturbed loess is much greater than that of remolded loess under the action of humidification.The relationship function of initial structural parameters between undisturbed loess and remolded loess is characterized by the indicators of structural yield pressure and compression index.The calculation model shows that the change of water content gradually reduces the influence of soil compression index and initial structure which increases with the increase of compactness,but has a significant influence on structural yield pressure.