结构性对黄土抗剪强度的影响研究

为揭示结构性对原状黄土和重塑黄土抗剪强度的差异影响，以国道Ｇ310三门峡西至豫陕界段的黄土路基为研究背景，对具有相同含水率和干密度的原状黄土和重塑黄土进行一系列直剪试验和扫描电镜试验，对比分析了原状黄土与重塑黄土在抗剪强度和微观结构的差异及其机理。直剪试验结果表明:剪切过程中原状黄土的应力应变关系呈应变软化而重塑黄土的应力应变关系呈应变硬化；原状黄土的应变软化现象随着垂直压力的增大逐渐减弱；原状黄土的抗剪强度参数比重塑黄土的大。原状黄土和重塑黄土的抗剪强度均随黄土黏粒含量的减少而降低。微观试验结果表明:原状黄土具有清晰的骨架颗粒、明显的支架孔隙、密集的接触处胶结物，其完整的原生结构是使其抗剪强度高于重塑黄土的主要原因。

Influence of Structure on Shear Strength of Loess in Sanmenxia

In order to reveal the influence of structure on shear strength of intact loess and remolded loess,the loess subgrade in national highway G310 from the west of Sanmenxia to Henan-Shanxi provincial boundary segment was taken as the research background,a series of direct shear test and scanning electron microscopy(SEM)test were conducted on the undisturbed loess and remolded loess with the same water content and dry density.The differences of shear strength and microstructure and its mechanism between the undisturbed loess and remolded loess were analyzed.In the process of shearing,the shear stress-shear displacement curve of undisturbed loess is a strain-softening type while that of remolded loess is a strain-hardening type.The strain softening phenomenon of undisturbed loess decreases with the increase of vertical pressure.The shear strength of undisturbed loess is higher than that of remolded loess.The shear strength of undisturbed and remolded loess decreases with the decrease of clay content.The result of scanning electron microscopy test indicate that the undisturbed loess has clear skeleton particles,obvious support pores and dense cement at the contact points,and its complete primary structure is the main reason that makes its shear strength higher than that of remolded loess.