延安Q3黄土应力应变特性及其归一化性状研究

为研究延安原状Q3黄土应力应变关系特性，并总结其在不同含水率不同围压下的归一化性状，进行了一系列固结不排水三轴剪切试验。试验结果表明:延安原状Q3黄土的应力应变关系整体上随围压增大由弱硬化型向强硬化型转变，但在含水率极低且低围压条件下会呈现出一定的软化特性；基于Kondner双曲线模型，对原状Q3黄土进行应力应变归一化分析，含水率为5%和10.2%的Q3黄土在400 kPa以下的围压下不存在归一化性状，含水率为17%的Q3黄土在300 kPa以上的围压下存在归一化性状,含水率为22%、27%和32%的Q3黄土在200 kPa以上的围压下归一化性状较显著；通过比较，选用初始切线模量或极限偏应力作为延安原状Q3黄土的归一化因子，归一化效果较好；建立了不同含水率下延安原状Q3黄土应力应变关系的归一化方程，其预测值与试验值较接近。该方程对延安Q3黄土相关工程设计及工程经验的验证有一定参考价值。

Study on Stress-strain Characteristics and Normalized Characters of Q3 Loess in Yan'an

In order to study the stress-strain relationship of Q3 loess in Yan''an, and to summarize the normalized traits under different confining pressures of different water contents, a series of consolidated undrained triaxial shear tests were carried out. The results show that the stress-strain relationship of the undisturbed Q3 loess in Yan''an is generally changed from weakly hardened to strong hardened with the increase of confining pressure, but it will exhibit certain softening characteristics under the condition of extremely low water content and low confining pressure; Based on the Kondner hyperbolic model, the stress strain normalization analysis of the undisturbed Q3 loess was carried out. The Q3 loess with water content of 5% and 10.2% had no normalized characters under the confining pressure of 400 kPa or less. The Q3 loess with a water content of 17% has normalized characters under the confining pressure of 300 kPa or more. The normalized characters of Q3 loess with water content of 22%, 27% and 32% are more significant under the confining pressure of 200 kPa or more; By comparison, the initial tangent modulus or ultimate deviatoric stress is selected as the normalization factor of the undisturbed Q3 loess in Yan''an, and the normalization effect is better; The normalized equations of stress-strain relationship of Yan''an undisturbed Q3 loess under different water contents were established and the predicted values are close to the experimental values. This equation has certain reference value for the verification of Yan''an Q3 loess related engineering design and engineering experience.