摘要
为了探究土体干缩开裂问题,文章采用ERT技术,对黏性土开展了一维干缩开裂动态监测试验。配制初始状态饱和的泥浆试样,在自然条件下干燥,采用ERT技术获得试样干燥过程中的电阻值变化。结合试样的电阻值图像和裂隙图像,对土体干缩开裂规律进行了分析。研究结果表明:在干燥蒸发初期,土体电阻值随时间增加缓慢减小,其原因在于土体干燥收缩导致土颗粒间接触面积增大,颗粒水化膜变薄,进而使得土颗粒表面双电层导电性增强。随着干燥继续进行,气体进入土体内部,土体由初始饱和状态转变为非饱和状态,电阻值转为缓慢增加。当土体产生裂隙时,裂隙周围土体电阻值急剧增大,而未发育裂隙的土体电阻依然保持缓慢增加的趋势。通过对比试样电阻值变化曲线和裂隙图像,发现两者所呈现的裂隙发育位置和状态存在良好的一致性。因此,ERT技术能对干燥过程中土体裂隙发育进行有效的动态监测,准确掌握裂隙发育的时空动态信息,并且能提前预测裂隙发育的可能位置,为研究极端干旱气候作用下土体的工程性质响应提供了理想手段。
In order to investigate soil shrinkage and desiccation cracking process,one-dimensional desiccation cracking tests were conducted on Xiashu clay and monitored using the electrical resistivity tomography(ERT)technique.During the test,saturated slurry specimens are prepared and dried under a natural condition.The evolution of electrical resistivity of soil specimen is recorded during the drying process.Moreover,the desiccation cracking mechanisms are analyzed by comparing desiccation crack patterns and electrical resistivity images.Experimental results show that the electrical resistivity of soil specimen decreases slightly at the beginning of the drying process.This is because volumetric shrinkage results in an increase in the contact area between soil particles and the double layer thickness reduces.Thus,the electrical conductivity of double layer increases.With elapsed drying time,soil specimen becomes unsaturated and the electrical resistivity transits into the increasing phase.When crack initiates,the electrical resistivity near the crack increases significantly.Comparing the desiccation crack patterns and electrical resistivity images,it is found that there was a consistency in terms of crack position and condition.Therefore,the ERT technique is an effective method to dynamic monitor the development of desiccation cracks and particularly reliable to map their positions.It can be a proper technique for further study on soil engineering properties under extreme drought climate.
作者
骆晓伟
张宽
唐朝生
曾浩
王玥
谈云志
LUO Xiaowei;ZHANG Kuan;TANG Chaosheng;ZENG Hao;WANG Yue;TAN Yunzhi(School of Earth Sciences and Engineering,Nanjing University,Nanjing 210023,China;China Three Gorges University,Yichang 443002,China)
出处
《高校地质学报》
CAS
CSCD
北大核心
2018年第6期939-946,共8页
Geological Journal of China Universities
基金
国家自然科学基金项目(41572246
41772280)
国家自然科学基金重点项目(41230636)
优秀青年科学基金项目(41322019)
江苏省自然科学基金项目(BK20171228
BK20170394)
中央高校基本科研业务费专项资金联合资助
关键词
干缩开裂
高密度电阻率
ERT技术
导电特性
动态监测
desiccation cracking
high-density electrical resistivity tomography
ERT technique
electrical conductivity
dynamic monitoring
