黄土垂直节理细微观特征及发育机制探讨  

Discussion on microscopic, microcosmic characteristics and developmental mechanism of loess vertical joints

作　　者：冯立 张茂省[1] 胡炜[1] 董英[1] 孟晓捷 FENG Li;ZHANG Mao-sheng;HU Wei;DONG Ying;MENG Xiao-jie(Key Laboratory of Geo-hazards in Loess Area,Ministry of Land and Resources,Xi'an Center of Geological Survey,Xi'an,Shaanxi 710054,China)

机构地区：[1]中国地质调查局西安地质调查中心国土资源部黄土地质灾害重点试验室,陕西西安710054

出　　处：《岩土力学》2019年第1期235-244,共10页Rock and Soil Mechanics

基　　金：国土资源公益性行业科技专项经费项目(No.201511056-4);国家自然科学基金项目(No.41530640)~~

摘　　要：风积黄土垂直节理发育,在黄土塬边或岸边容易观测,受水环境变化影响极易诱发黄土灾害。以黄土垂直节理为研究对象,从黄土垂直节理细微观发育特征入手,总结了黄土垂直节理在横纵方向上发育规律,研究了黄土垂直节理在不同评价尺度上的展现形式、转换机制及形成垂直节理的微细观结构基础。从黄土的沉积动态出发,探讨了垂直节理的垂向发育机制。研究结果表明:垂直节理是黄土在历史沉积过程逐渐形成的,是成岩过程的产物,提出了黄土中存在的孔隙集中带及垂直管状通道是能够发育垂直节理的微细观结构基础,三维CT扫描试验结果为其提供了强有力的证据;其在不同评价尺度上的展现形式不同,在外部作用下(干湿循环作用及黄土堆厚)其垂直节理在微-细-中观是可以向上尺度(扩张特征)或者向下尺度(衰退特征)发育、发展转换的,即尺度转换机制;并借此提出了黄土垂直节理的垂向发育机制。It is easy to observe the development of vertical joints of aeolian loess on the edge or shore of a plateau, and these vertical joints can readily induce loess disasters due to changes in the water environment. The vertical joints of loess were investigated in this study. The developmental laws of vertical joints of loess in horizontal and vertical directions were summarized based on their meso-microscopic developmental characteristics. The display forms, transformation mechanisms and the micro-mesoscopic structural basis for forming vertical joints of loess were observed on different evaluation scales. Based on the sedimentary dynamics of loess, the vertical developmental mechanism of vertical joints was discussed. Studies had shown that vertical joints formed gradually during the historical sedimentary process and were the product of diagenesis. It was proposed that the pore concentration zone and vertical tubular channel in loess were the micro-mesoscopic structural basis for the development of vertical joints, for which the results of a three-dimensional CT scanning test provided strong evidence. The vertical joints exhibit different forms on different evaluation scales. Under external actions(wet and dry cycling and loess pile thickening), the vertical joints in the micro-meso-sub-macro point of view can be developed in an upward scale(expansion characteristics) or downward scale(decay characteristics), and they can transform between the two scales. This is referred as the scale conversion mechanism. The vertical developmental mechanism of vertical joints of loess was also proposed based on this.

关 键 词：垂直节理 结构单元 尺度转换 发育机制 

分 类 号：TU411[建筑科学—岩土工程]