陇东Q3结构性黄土压剪损伤本构模型试验研究

Q3黄土在我国西北地区分布广泛，且大部分都具有显著的结构性。随着国家“一带一路”倡议的不断向前推进，作为丝路沿线的西北黄土分布地区将迎来新的建设大潮。黄土的结构变形特性非常复杂，深入研究黄土在压缩、剪切条件下的结构损伤变形特性，并依此构建黄土的本构关系在理论研究及现场工程应用中具有非常重要的意义。通过对黄土进行均等压缩试验及三轴剪切试验，基于损伤力学思想，提出黄土结构在均等压缩条件下的平均正应力损伤比，在剪切条件下的平均正应力损伤比及偏应力损伤比。根据弹性、塑性应变确定塑性势线，进而确定其屈服函数；将确定的黄土结构损伤比引入到屈服函数中，得到一定结构损伤时黄土的屈服函数表达式；验证了选取塑性体应变作为本构模型硬化参量的合理性；根据硬化参量与相关试验参数的联系，推导出结构性黄土在压剪条件下的损伤本构模型。经过实测应力-应变曲线与本构模型推算得到的应力-应变曲线对比可知，所建立的本构模型可以较好地反映黄土在压剪条件下结构损伤演化变形过程，具有较好的工程应用前景。

Experimental study of constitutive model of Longdong Q_3 structural loess with compressive and shearing damage

The Q3 loess is widely distributed in the northwest of China, and most of them present significant structural characteristics. With the development of the national “The Belt and Road” Initiative, as the northwest loess areas along the silk road will usher in a new tide of construction. The structural deformation characteristics of loess are very complex. In-depth study of the structural damage and deformation characteristics of loess under compression and shearing conditions is of great significance for constructing the constitutive relation of loess in theoretical research and field engineering application. Through the three-axis isotropic compression test and the three-axis shear test, the ball stress damage ratio of the loess structure, the ball stress damage ratio and the shear stress damage ratio are proposed. According to the elastic and plastic strain of the plastic potential line, and its yield function, the damage ratio of loess is introduced to the yield function, and expressed under structural damage. The rationality of selecting the plastic volumetric strain as the hardening parameter is verified. According to the relationship between hardening parameter and the test parameters, damage constitutive model of structural loess under the condition of compression and shear is derived. By comparing the measured stress-strain curves with the calculation from the constitutive model, we can see that the constitutive model can better reflect the structural damage evolution and deformation process of loess under compression and shearing condition.