黄土剪切蠕变特性试验研究

EXPERIMENTAL STUDY OF SHEAR CREEP CHARACTERISTICS OF LOESS

通过对陕西杨凌地区Q3黄土的直接剪切蠕变试验,研究原状、重塑和饱和黄土的蠕变特性。结果表明:原状、重塑和饱和黄土均具有蠕变特性;相同试验条件下,饱和黄土的蠕变速率最快,蠕变变形量最大,重塑黄土次之,原状黄土蠕变现象较不明显。根据蠕变曲线形态特征,建议一种对数型蠕变模型;选用分数线性蠕变模型模拟杨凌地区Q3黄土的剪切蠕变特性,经验证,该模型能很好地描述杨凌地区Q3黄土的剪切蠕变特性。另外,基于试验数据,拟合出剪切模量和法向应力、时间的关系,为确定剪切模量提供一条新途径。

By taking the Q3 loess of Yangling district in Shaanxi province as the research object, a direct shear creep test is conducted to investigate the characteristics of creep behavior of intact loess, disturbed loess and saturated loess. The experimental results indicate that the intact loess, the disturbed loess and saturated loess all have creep characteristics; under the same experimental conditions, the creep strain rate of saturated loess is the fastest and the creep strain is the biggest among the three kinds of loess samples. The creep characteristics of disturbed loess is less obvious than that of saturated loess and it is least obvious in intact loess. According to the characteristics of creep curves, a new logarithm model is suggested; and based on the typical creep behavior of loess, the fraction-linearity creep model is used to simulate the shear creep characteristics of Yangling Q3 loess according to the fitting results, the parameters of model are obtained; the model better simulates the creep characteristics of Q3 loess in Yangling district by model test. Besides, based on the experimental data, the relation between shear modulus and normal stress and time is fitted, and a new method to confirm the shear elastic module is supplied.