Q2黄土蠕变特性的水化学作用效应研究

The macro creep behavior of Q2 loess is associated with the distribution and content of calcareous cement. The calcareous cement could be chemically damaged by some acid solutions such as acid rain and acid mine drainage, thus its macro creep behavior can be significantly affected after the Q2 loess was soaked. But how does the hydro-chemical effect affect the creep behavior of Q2 loess is an important problem to be analyzed. To that end, this project intends to carry out the soak tests under different conditions (pH value and concentration) within different time periods for Q2 loess, and to conduct microscopic test, macro compression and creep test for saturated Q2 loess under different soaked conditions and original Q2 loess. The variability of microstructure, composition and creep mechanical property of Q2 loess before and after hydro-chemical effect will be analyzed in-depth. Based on this, by using the variable order fractional calculus and damage mechanics, the nonlinear creep model of Q2 loess that can reflect chemical damage effect of acid solution will be constructed. Meanwhile, these models will be further developed with a compiler to simulate Q2 loess slope time-dependent deformation behavior. The research results can provide theoretical support for stability analysis of Q2 loess slope under hydro-chemical effect.

Q2黄土中的钙质胶结物分布及含量关联其宏观蠕变特性，而诸如酸雨、矿山酸性排泄水等酸性溶液对这种钙质胶结物具有化学损伤作用，浸泡接触后显著影响其宏观蠕变特性。但水化学作用对Q2黄土蠕变特性具体是如何影响则是一个亟待解决的重要问题。为此，本项目拟采用不同pH值及浓度的酸性溶液对Q2黄土进行不同时间下的浸泡试验，并针对不同浸泡试验状态的饱和Q2黄土及原状Q2黄土开展微观测试及宏观压缩与蠕变试验，深入分析水化学作用前后Q2黄土微观结构、成分、蠕变力学特性等变化情况；并在此基础上借助变分数阶微积分及损伤力学等技术构建可反映化学损伤的Q2黄土非线性蠕变模型；同时基于编译程序实现前述本构模型二次开发，并应用于Q2黄土边坡时效变形模拟计算。研究成果可为水化学作用下Q2黄土边坡稳定性分析提供理论支持。

Q2黄土的宏观蠕变特性受控于其自身的结构状态，而黄土颗粒之间的钙质胶结状态则深深的影响其结构稳定性。随着人类活动的增强，酸雨及矿山酸性排泄水等具有酸性特征的溶液在影响Q2黄土蠕变力学特性方面表现的越来越明显。为了探究Q2黄土蠕变特性的水化学作用效应，本项目开展了不同酸蚀程度的Q2黄土宏观三轴试验、宏观蠕变试验及微观结构观测试验；分析了酸液浸泡浓度和浸泡时间与Q2黄土孔隙的对应变化关系；破解了Q2黄土抗剪参数、弹性模量、蠕变长期强度等随酸液浸泡浓度与浸泡时间的变化规律；揭示了酸性溶液作用影响黄土微观结构的机理。在此基础上，提出了两个可以描述酸蚀Q2黄土蠕变特性的蠕变模型，并推导给出了其三维蠕变方程。最终为Q2黄土边坡于酸性溶液作用影响下的时效变形计算提供了依据。