摘要
湿干冻融耦合作用(WDFT)是导致寒区膨胀土地基发生劣化现象的重要因素,而膨胀土地基裂隙发育的方向对工程安全稳定存在长期影响。围绕膨胀土裂隙发育的方向性问题,采用自行设计的单向环境边界加载装置,开展了WDFT边界条件下表面裂隙发育特征的大尺寸试样单元试验,运用数字图像采集与处理方法得到了不同WDFT循环下的表面裂隙发育特征。试验结果表明,冻结过程中膨胀土内部液态水含量对表面裂隙的分布及形态产生重要影响,当临界饱和度较大时,冻结过程对裂隙起到促进作用,反之则为抑制作用;而在后期WDFT下的裂隙率逐渐趋于稳定。在此基础上,以裂隙图像灰度直方图为基础,通过梯度方向法对裂隙发育的局部方向性进行了统计,引入无量纲影响因子对裂隙角度进行了量化归纳,进一步探讨了膨胀土在下的裂隙演化规律。所采用的量化分析方法可为相关研究提供参考。
The wetting-drying and freeze-thaw(WDFT)coupling effect is an important factor leading to the deterioration of the expansive soil foundation in the cold regions,and the direction of fissure development in the expansive soil foundation has a profound impact on the long-term safety and stability.Focusing on the directionality of crack development in expansive soils,a unit test of the characteristics of surface crack development under WDFT coupling boundary conditions is carried out using the self-designed unidirectional environmental boundary loading device,and the digital image acquisition and processing methods are used to obtain characteristics of surface fissure development under WDFT coupling cycle.The test results show that the liquid water content in the expansive soil during freezing has an important effect on the distribution and morphology of surface cracks.When the critical saturation is large,the freezing process promotes the cracks,and vice versa.The fracture rate gradually stabilizes at later stage of WDFT.Based on the gray histogram of the fissure image,the local directionality of fissure development is calculated by the gradient direction method,and the dimensionless influence factor is introduced to quantify and summarize the fissure angle.The crack evolution laws of expansive soil are further investigated.The quantitative analysis method used can provide reference for related researches.
作者
张晨
朱洵
黄英豪
郭万里
韩迅
ZHANG Chen;ZHU Xun;HUANG Ying-hao;GUO Wan-li;HAN Xun(Geotechnical Engineering Department,Nanjing Hydraulic Research Institute,Nanjing 210024,China)
出处
《岩土工程学报》
EI
CAS
CSCD
北大核心
2020年第S01期234-238,共5页
Chinese Journal of Geotechnical Engineering
基金
国家重点研发计划项目(SQ2017YFSF020086)
国家自然科学基金项目(51709185,51879166)
中央级公益性科研院所基金基本科研业务费项目(Y320010)
关键词
膨胀土
干湿、冻融循环耦合
裂隙发育
单元试验
裂隙方向
expansive soil
coupling wetting-drying and freeze-thaw
fissure
sample test
directionality
作者简介
张晨(1988-),男,高级工程师,博士,主要从事岩土工程测试方面的研究工作。E-mail:czhang@nhri.cn。
