不同地区黄土的结构性试验研究

Experimental Study on Structural Characteristics of Loess in Different Regions

考虑不同地区黄土的结构性差异,选取洛川、兰州和杨凌3地的典型黄土,分别进行三轴剪切试验,测定了应力应变关系曲线。基于Duncan-chang双曲线模型,提出了一种简便求取结构性参数的方法,得出了这3个地区的黄土结构性参数的变化规律,较好地揭示了它们的结构性的变化规律和影响因素。结果表明,非饱和黄土的结构性参数随应变的增大先降低,而后保持在一个稳定的水平。含水率与围压对黄土的结构性影响显著。在相同的围压条件下,含水率越低,黄土的结构性参数越大;在相同的含水率条件下,围压越小,黄土的结构性参数越大。对不同地区而言,在相同条件下杨凌黄土的结构性最强,洛川黄土次之,兰州黄土结构性最弱。

Triaxial shear tests were conducted to measure stress-strain curves under the consideration of loess structural differences in different regions. Three different typical loess areas of Luoehuan, Lanzhou, and Yangling were selected. Based on Duncan-chang hyperbolic model, a simple way was adopted to determine structural parameters, which is better to reveal the changes and factors of structural parameters. The change in the structural parameters of the three regions was found. Results showed that unsaturated loess structural parameters firstly decreased with the increase in shear strain and then remained at a stable level. Water content and consolidation stress had significant influences on structural parameters. Under the same pressure condition, the lower the moisture content, the greater the structural parameters of loess and under the same moisture condition, the smaller the pressure, the greater the structural parameters of loess. As far as different regions are concerned, the strongest structural characteristic of loess under the same conditions was Yangling loess and it was followed by Luochuan loess. Lanzhou loess structure was the weakest.