摘要
冻融环境下黄土物理力学性质劣化是寒区工程建设必须要考虑的问题之一,取延安市黄陵县黄土为研究对象,以初始含水率、冻融循环次数为变量,借助扫描电子显微镜、Leica Qwin、Canny算子边缘检测、分型理论定量评价冻融环境下黄土微观结构损伤状态;通过GDS探究不同初始含水率、不同冻融循环次数对试样强度指标的影响,并用显著性理论进行评价。结果表明:随着冻融次数的增加试样内部裂隙不断发育演化,土体内部的大颗粒不断分解为若干小颗粒,骨架连接方式发生转变,由面-面接触转变为点-面、点-点接触;随着冻融循环次数的增加面孔隙度、分形维数不断增大,冻融循环10次后趋于稳定,试样在冻融环境下内部微、小孔隙不断向中、大孔隙转化;随着冻融循环次数的增加试样的黏聚力不断减小,内摩擦角不断增大,冻融10次后强度指标趋于稳定,试验结果与图像探伤结论相一致;对试样黏聚力、内摩擦角进行显著性分析可知冻融循环次数、初始含水率及其交互作用(耦合作用)对试样强度指标有特别显著的影响。
The deterioration of the physical properties of loess under freezing and thawing conditions is one of the concerns that must be taken into consideration when construction in the cold regions. In this paper,a variety of loess samples with different water contents were taken from Huangling County of Yan＇ an Prefecture as research objective to further study the physical change of the loess while exposing in freezing-thawing environment. The microstructure alternations of loess under freezing and thawing condition were evaluated by means of scanning electron microscope,edge detection and quantitative classification; the correlationship between the moisture content of the samples and various freezing-thawing cycles were revealed,as well as the changes of strength index of the samples through GDS and its degree of significance. The results showed that the grain fracture grows with the increase of freezing thawing cycles,the large particles are continuously broken down into smaller particles,the skeleton connection mode changes from surface to surface contact to point to point contact; with the increase of the number of freezing-thawing cycles,the fractal dimension increases; after 10 freezing-thawing cycles,the porosity and fractal dimension tend to be stable; with the increase of freezing-thawing cycles,the cohesion of the sample decreases,the internal friction angle increases continuously,and the strength index tends to be stable after10 freezing and thawing cycles. The experimental results are consistent with the scanning results of SEM; by analyzing the cohesion and internal friction angle of specimens,it can be seen that the freezing-thawing cycles,initial water content and their interaction（coupling action） have particularly significant effects on the strength index of the samples.
作者
叶万军
李长清
董西好
刘忠祥
彭瑞奇
王岩
吴云涛
孙瑞梁
魏伟
YE Wanjun;LI Changqing;DONG Xihao;LIU Zhongxiang;PENG Ruiqi;WANG Yan;WU Yuntao;SUN Ruiliang;WEI Wei(School of Architecture and Civil Engineering,Xi＇an University of Science and Technology,Xi＇an 710054,China)
出处
《冰川冻土》
CSCD
北大核心
2018年第3期546-555,共10页
Journal of Glaciology and Geocryology
基金
国家自然科学基金项目(41672305
41172262)
国家自然科学基金青年项目(51509200)
陕西省重点科技创新团队计划项目(No.2014KCT-30)资助
关键词
冻融
边缘检测
分型理论
显著性分析
freezing-thawing
edge detection
fractal theory
significance analysis
