风积再造黄土结构演化机制解译

Geohazards in loess prevent the infrastructure construction and safe services in Western China. It is thought that the weak structure of loess is responsible for such geohazards. Scholars in the field of engineering geology achieved some advances on the structure of present-day intact and remolded loess samples. However, the structure of present-day loess is the result of long-term geological processes. It is still mysterious how the loess evolves from the original aeolian structure all the way towards the present-day structure, which is loose, porous, heterogeneous and anisotropic. This project tends to prepare the aeolian loess by simulating the aeolian environment. Physical simulations will be conducted on the aeolian loess samples by considering environmental factors, such as temperature fluctuation, humidity variation, rainfall, evaporation and loading. Three-dimensional structure models will be constructed, by using CT scanning technology, for the original aeolian loess and those experienced structure evolutions driven by environmental factors. The influences of the above environmental factors on evolution of loess structure will be interpreted by analyzing the structural parameters extracted from the 3D structure models. Big-data analytics is going to be adopted to deal with the voluminous and complex data sets, which are yielded from the 3D structure models. A big-data platform will be set up in order to perform the data mining for clarifying the correlations between environmental factors and structure evolution of aeolian loess. A sophisticated mathematical model will be constructed based on the big-data analytics and verified by a physical model with all environmental factors working together. The results of this study will be capable of deciphering the evolution process of aeolian loess structure, predicting the future evolution of present-day loess, and providing important theoretical theory and methodological guidance for the prevention of geohazards in loess-covered areas.

黄土地质灾害一直困扰我国中西部基础工程建设和安全运营，导致该问题的根本原因是黄土结构的脆弱性。长期以来，研究者聚焦于现今的原状黄土或重塑黄土，开展黄土结构研究，完成了一些尝试性工作。然而，现存黄土的结构是地质历史演化的结果。黄土是如何从初始风积结构逐步演变成现今的松散、多孔隙、各向异性结构仍不得而知。本项目将模拟黄土风积环境，再造风积黄土；采用物理试验，模拟环境因素（温度、湿度、降雨、蒸发和上覆荷载）对风积黄土结构的改造；借助CT扫描及三维结构重建技术，构建系列黄土三维结构模型，提取三维结构参数，分析环境因素对风积黄土结构演化的作用方式和作用强度；同时，引入大数据解析法，搭建黄土结构大数据分析平台，构建、检验并修正各环境因素耦合作用下风积黄土结构演化模型，解析风积黄土的结构演化机理，解密风积黄土的结构演化历程，用以预测黄土结构的未来演化趋势，为黄土地质灾害预防提供重要的理论依据和方法指导。

黄土地质灾害一直困扰着我国中西部基础工程的安全建设和运营，导致该问题的根本原因是现今黄土结构的脆弱性。现今黄土结构是初始风积黄土在漫长的地质历史时期经受各种环境因素作用逐渐演化而来的。而以往针对黄土结构演化所开展的研究主要聚焦于现今的原状黄土、重塑或压实黄土，相关研究成果无法简单推延和应用于初始风积黄土。故而，现今黄土结构是如何形成的，仍不得而知。本项目通过模拟黄土风积环境，再造了初始风积黄土；开展了其在环境因素（温度循环、湿干交替、冻融循环和上覆荷载）作用下的结构演化物理模拟试验；借助影像动态捕捉、CT扫描及三维结构重建技术，提取了风积黄土的二维、三维结构参数，分析了环境因素对风积黄土结构演化的作用方式和作用强度；结合离散元数值模拟和理论分析，探明了风积黄土的结构演化机制。研究成果揭示了风积黄土的结构演化历程，可用于预测黄土结构的未来演变趋势，为黄土地质灾害的有效预防提供重要的理论依据和方法指导。