延安Q2黄土三轴蠕变特性试验研究

对延安地区Q₂黄土进行了三轴蠕变试验，通过试验得到了延安Q₂黄土不同含水率及不同围压条件下应变-时间曲线和应力应变等时曲线。经过曲线分析发现，应力水平、围压及含水率对延安Q₂黄土的蠕变特性具有较大影响，且当应力水平高于试样的屈服应力时，Q₂黄土表现出显著的非线性蠕变特性。根据蠕变试验结果及模型原理，利用类比法建立了三维应力状态下的黏弹塑性蠕变模型。在此基础上，建立了考虑瞬时损伤的黄土蠕变本构模型，并运用拟牛顿法对模型中的各项参数进行拟合，结果表明：该本构模型适用于延安地区Q₂黄土的蠕变研究，同时，期望该研究成果能为黄土高原其他地区岩土工程设计提供理论及实践意义。

Triaxial Test on the Creep Characteristics of Q2 Loess in Yan' an

Triaxial creep tests are performed on Yan''an Q₂ loess to obtain the triaxial creep curves and stress-strain isochronous curves under different water contents and confining pressures. Analysis on the curves reveals that stress magnitude, confining pressure and water content has great impact on the creep characteristics of Yan''an Q₂ loess, and when the stress is higher than the sample''s yield stress, obvious nonlinear creep characteristic is found. The visco-elasticity-plasticity creep model of the loess is established by analogy in line with the modeling theory and the test results. On the basis of these, the visco-elasticity-plasticity constitutive creep model of the loess considering instantaneous damage is established, and the relevant parameters are fitted by Quasi-Newton method. The applicability of this constitutive model is verified by comparison between theoretical curve and experimental curve. The research results are of theoretical and practical value for the geotechnical engineering in the loess plateau.