黄土抗剪强度的水敏感性特征研究

抗剪强度是黄土重要的力学性质指标，在不同的含水状态下，土体抗剪强度存在明显差异。黄土属水敏感性地质体，在水的软化作用下。黄土抗剪强度特征与应力-变形机制呈现出明显的规律性。在荷兰尤怀特大学、英国莱斯特大学和兰州大学对不同沉积时代黄土样品直接剪切、环剪及原位大面积剪切试验的基础上，重点研究不同含水状态下不同沉积年代黄土抗剪强度的水敏感性机制与应力-应变特征。根据室内和原位测试结果，对黄土抗剪强度的基本规律进行分析和总结，提出黄土抗剪强度特征与应力-变形机制发生转变的特征含水量We-脆-塑转捩界限含水量，对黄土脆-塑转捩界限含水量的标准与变化范围进行研究，划分黄土类脆性变形和类塑性变形的界限，在此基础上给出黄土抗剪强度公式，揭示不同沉积时代与含水状态下黄土抗剪强度的水敏感性特征及应力-变形机制。

RESEARCH ON WATER SENSITIVITY OF LOESS SHEAR STRENGTH

Shear strength is the most important mechanical index of loess, which strongly depends on the loess deposit age and moisture content. Loess is a special deposit, and it is very sensitive to water under the softening action of water. Shear strength and deformation curve of loess change with obvious paws. Based on the data of a large number of loess tests of direct shear, ring shear and in-situ direct shear carded out in Utrecht University, Leister University and Lanzhou University, here, the effects of the water content and the depositing age on the shear strength, and the stress-strain relationship of loess are studied. As a new index, the critical moisture content is proposed, which characterizes the turning point between the brittle and plastic deformation ranges on the deformation curve. Light is also shed on the underlying mechanism of the dependence of the loess shear strength and deformation rule on its depositing age and moisture content. According to the results of loess shear strength with different moisture contents and different ages, the boundary of the brittle and plastic deformation, and develop some important equations of shear strength for loess are presented.