结构性黄土压缩屈服特性及湿压模型

STRUCTURAL YIELD BEHAVIOR OF COLLAPSIBLE LOESS AND ITS ONE DIMENSIONAL CONSTITUTIVE MODEL UNDER MOISTURE AND COMPRESSION

湿陷性黄土具有很强的结构性,在增湿及侧限压缩应力作用下,其变形特性表现出与一般黏性土不同的特性。针对这一问题,通过对3种不同初始结构性黄土的侧限压缩试验,对黄土在增湿及压缩应力条件下黄土的宏观力学特性及其结构变化特征进行研究。研究结果表明:1)在增湿及侧限压缩应力作用下,黄土的e-lgp曲线分成三段,即平缓状态段、非线性段和线性段;2)原状黄土的压缩曲线与重塑土压缩曲线的变化给出了同一压力下黄土架空排列结构破损后孔隙比的可能变化量;3)原状黄土与饱和黄土压缩曲线的差别揭示了同一压力下黄土颗粒间胶结丧失后结构性黄土孔隙比的可能变化量;4)结构屈服应力与初始含水率之间满足幂函数关系,压缩指数与初始含水率之间呈指数函数关系。

The structure of collapsible loess is very strong,whose deformation characteristics are different from those of general clay under the moisture and compressive stress. It was researched the macroscopic mechanical properties and structural variation laws of the loess,based on the confined experiments of three loesses with different initial structure. And the results showed that: firstly,under the above two effects,the e-lgp curves of loess were divided in three sections, flat segment, nonlinear segment and linear segment. Second, there was a void ratio on two compression curves between undisturbed loess and remold loess when the structural damage emerging under remolding and compression at the same compressive stress. Thirdly,there was a similar void ratio between undisturbed loess and saturated loess moisture and compression. At last,it was revealed that there was a power function relationship between the structural yield stress and initial water content,while there was an exponential function relationship between compression index and initial water content.