摘要
为了研究水泥改良风积沙发生冻融损伤后的动应力-应变特征,利用GDS冻土动态测试系统分析了水泥改良风积沙在不同负温条件下多次冻融循环后的动力变形特征,利用扫描电子显微镜(SEM)对多次冻融后的沙粒间孔隙演化特征进行了细观扫描。提出了基于二分法原理的临界动应力试验方法及其负指数衰减规律,利用MATLAB图像处理技术对冻融损伤后的水泥改良风积沙内部各组成部分比例进行确定,并计算出冻融损伤后孔隙的分形维数。构建了强度参数与温度和孔隙分形维数的数学联系,利用单元强度的Weibull分布规律确定了改良沙冻融循环损伤变量,建立了具有分形特征的改良风积沙冻融损伤本构模型。利用Weibull分布确定了改良沙发生冻融循环后的损伤变量参数,提出了具有分形特征的改良风积沙冻融循环损伤动荷载本构关系,为路基动力灾害防治提供理论依据。结果表明:利用二分法原理可确定改良风积沙临界动应力,随着冻融次数的增加,临界动应力具有衰减的特征并且衰减的速度会减慢;随着冻融次数的增加,SEM观测的区域内的孔隙分布区域不断扩大,水泥填充物逐渐退化,边缘不规则程度逐渐加剧,孔隙分形维数随之提高,但是孔隙在发展过程中局部相对于整体上具有高度的自相似特征。
In order to study the dynamic stress-strain characteristics of cement modified aeolian sand after freeze-thaw damage,the dynamic deformation characteristics of cement modified aeolian sand after multiple freeze-thaw cycles under different negative temperature conditions are analyzed by using GDS dynamic frozen soil testing system,and the pore evolution characteristics among sand particles after multiple freeze-thaw cycles are scanned microscopically with scanning electron microscope(SEM).A critical dynamic stress testing method and its negative exponential attenuation rule based on the dichotomy principle are proposed,the proportions of internal components of cement modified aeolian sand after freeze-thaw damage are determined by using MATLAB image processing technology,and the fractal dimensions of pores after freeze-thaw damage are calculated.The mathematical relationships among strength parameters,temperatures and pore fractal dimensions are established,the freeze-thaw cycle damage variables of modified aeolian sand are determined by using Weibull distribution rule with unit strength,and the constitutive models of freeze-thaw damage of modified aeolian sand with fractal characteristics are established.The damage variable parameters of modified aeolian sand after freeze-thaw cycles are determined by Weibull distribution,and the dynamic load constitutive relationships of modified aeolian sand freeze-thaw cyclic damage with fractal characteristics are proposed for providing a theoretical basis for the subgrade dynamic disaster prevention.The result shows that(1)The critical dynamic stress of modified aeolian sand can be determined by using the dichotomy principle.The critical dynamic stress is characterized by attenuation and the rate of attenuation slows down with the increase of freeze-thaw cycles.(2)With the increase of freeze-thaw cycles,the distribution area of pores expands continuously in the SEM observed area,the cement filler degenerates gradually,the degree of edge irregularity intensifies gradually,and
作者
易富
李丰
李军
YI Fu;LI Feng;LI Jun(School of Architecture and Transportation,Liaoning Technical University,Fuxin Liaoning 123009,China;Shijiazhuang Power Supply Branch of State Grid Hebei Electric Power Co.,Ltd.,Shijiazhuang Hebei 050000,China;Shijiazhuang Electric Power Design and Research Institute Co.,Ltd.,Shijiazhuang Hebei 050030,China;School of Civil Engineering,Liaoning Technical University,Fuxin Liaoning 123009,China)
出处
《公路交通科技》
CSCD
北大核心
2023年第7期18-27,共10页
Journal of Highway and Transportation Research and Development
基金
国家自然科学基金项目(51774163)
辽宁工程技术大学首批“双一流”学科建设创新团队资助项目(LNTU20TD-26)。
关键词
道路工程
损伤机理
二分法
水泥改良风积沙
图像处理
road engineering
damage mechanism
dichotomy
cement modified aeolian sand
image processing
