重塑南宁膨胀土宏细观特征的各向异性试验  

Anisotropy of macro and micro characteristics of remolded Nanning expansive soil

作　　者：谭波[1,2] 潘政安[1,2] 唐双美 徐良 孙广 王静 TAN Bo;PAN Zheng'an;TANG Shuangmei;XU Liang;SUN Guang;WANG Jing(College of Civil Engineering,Guilin University of Technology,Guilin 541004,China;Guangxi Key Laboratory of Geomechanics and Geotechnical Engineering,Guilin University of Technology,Guilin 541004,China;Guangxi Road Construction Engineering Group Co.,Ltd.,Nanning 530001,China;Haian Construction Development Investment Group Co.,Ltd.,Haian 226600,China)

机构地区：[1]桂林理工大学土木工程学院,广西桂林541004 [2]桂林理工大学广西岩土力学与工程重点实验室,广西桂林541004 [3]广西路建工程集团有限公司,南宁530001 [4]海安市城建开发投资集团有限公司,江苏海安226600

出　　处：《桂林理工大学学报》2024年第3期424-431,共8页Journal of Guilin University of Technology

基　　金：国家自然科学基金项目(51768015);广西自然科学基金项目(2017GXNSFAA198092)。

摘　　要：为了揭示膨胀土细观结构对宏观膨胀差异的影响规律,以南宁重塑膨胀土为研究对象,利用自研的三向膨胀仪开展宏观试验,获得干密度对于膨胀率的影响规律。通过CT扫描试验研究其细观孔隙和土颗粒结构;基于Avizo软件对孔隙和颗粒的细观特征、孔隙的分形特征进行系统分析;并结合三向宏观试验共同揭示了细观结构特征对宏观膨胀变形的影响规律。结果表明:试样的两个水平方向膨胀率基本一致,竖向大于横向;干密度增大,横、竖向膨胀率比值越趋近于1。竖、横向孔隙率之比随着干密度的增大而增大;当横、竖向膨胀率之比越趋近于1;竖、横向孔隙率之比越大,说明横、竖向孔隙率与宏观横、竖向膨胀率存在较好的关系;竖、横向土颗粒粒径之比随着干密度的增大而减小;横、竖向膨胀率之比越趋近于1,竖、横向土颗粒粒径之比越小,说明横、竖向土颗粒粒径与三向膨胀率也存在较好的关系;孔隙分形维数用来表征孔隙复杂程度,与三向膨胀率并无直接关系。In order to reveal the influence of expansive soil meso structure on the macro expansion,Nanning remolded expansive soil was studied.The macro test is carried out by self-developed three-dimensional dilatometer to obtain the influence law of dry density on expansion rate.The meso pore and soil particle structure are studied through CT scanning test.The meso characteristics and fractal characteristics of pores and particles are systematically analyzed based on Avizo software.Combined with three-dimensional macro test,the influence of meso structure characteristics on macro expansion deformation is revealed.The results show that the horizontal expansion rates of the sample are basically the same.The vertical expansion rate is greater than the horizontal expansion rate.With the increase of dry density,the ratio of horizontal-vertical expansion rate is close to 1.The ratio of vertical-horizontal porosity increases with the increase of dry density;When the ratio of horizontal-vertical expansion is close to 1,the ratio of vertical-horizontal porosity is larger,indicating that there is a good relationship between horizontal-vertical porosity and macro horizontal-vertical expansion.The ratio of vertical-horizontal soil particle size decreases with the increase of dry density.When the ratio of horizontal-vertical expansion rate is close to 1,the ratio of vertical-horizontal soil particle size is smaller,indicating that there is also a good relationship between horizontal-vertical soil particle size and three-dimensional expansion rate pore fractal dimension is used to characterize pore complexity,which is not directly related to three-dimensional expansion rate.

关 键 词：膨胀土 CT扫描 颗粒粒径 细观特征 各向异性 

分 类 号：TU443[建筑科学—岩土工程]