摘要
对两种状态的压实黄土进行了一维常含水率压缩试验及常应力增湿试验,结合压汞法及扫描电镜等细观结构研究手段,对压缩以及增湿作用下压实黄土的细观结构演化进行分析,进一步对压实黄土在水力耦合作用下的细观变形机制进行探讨。研究结果表明:常含水率压缩下,压实黄土饱和度增大,可以在进一步压缩下发展为饱和土的固结过程;细观层面上非饱和压实黄土的压缩是其大孔隙在应力作用下塌陷减少的结果,而小孔隙分布在压缩中不受影响;常竖向应力下增湿,压实黄土的湿化变形随着竖向应力的增大呈现先增大后减小的趋势,最大湿化应变发生在压实应力附近。细观层面上,湿化作用下,颗粒及团聚体之间的黏结弱化,发生崩塌滑移,大孔隙塌陷减小而小孔隙增多,湿化后土体结构趋于均匀稳定。而压实黄土的蠕变也是在恒定荷载作用下土颗粒或团聚体的蠕滑、大孔隙进一步压缩引起的。结合研究结果,进一步从细观角度对黄土高填方施工期及工后期沉降进行总结阐述。
In this paper, a large number of one-dimensional tests, including constant water content compression and soaking under constant stress, are conducted. The microstructure evolution and deformation mechanism of the compacted loess under loading and wetting conditions are investigated with mercury intrusion porosimetry(MIP) and scanning electron microscope(SEM) analysis. Experimental results show that, as the saturation of compacted loess increases at a constant moisture content, it will develop into a saturated consolidation process under further compression. At the microscopic level, the compression of the unsaturated compacted loess results from the collapse reduction of its macrospores, while the distribution of microspores is unaffected in compression. During increasing wetting under the constant vertical stress, the wetting deformation of compacted loess shows a trend of increasing and then decreasing with the increase of vertical stress, and the maximum wetting strain occurs near the compaction stress. Under wetting conditions, the bonds between particles and aggregations are weakened, and the particles and agglomerates collapse and slip, resulting in the reduction of macrospores and the increase of microspores. Also, the soil structure tends to be more uniform and stable after wetting. The creep of compacted loess is caused by the further slippage of particles under constant load and further compression of macrospores. In addition, the settlement law of compacted loess fill is summarized from the construction and post-construction period according to testing results.
作者
葛苗苗
李宁
盛岱超
朱才辉
PINEDA Jubert
GE Miao-miao;LI Ning;SHENG Dai-chao;ZHU Cai-hui;PINEDA Jubert(College of Civil Engineering and Architecture,Wenzhou University,Wenzhou,Zhejiang 325035,China;Institute of Geotechnical Engineering,Xi'an University of Technology,Xi'an,Shaanxi 71004&China;University of Technology Sydney,Sydney,Australia;The University of Newcastle,Newcastle,Australia)
出处
《岩土力学》
EI
CAS
CSCD
北大核心
2021年第9期2437-2448,共12页
Rock and Soil Mechanics
基金
国家自然科学基金项目(No.52008317)
陕省岩土与地下空间工程重点实验室开放基金项目(No.YT202006)。
关键词
压实黄土
一维压缩及增湿试验
细观试验
孔隙分布
湿化变形
compacted loess
one-dimensional compression and wetting test
microstructure analysis
pore size distribution
deformation upon wetting
作者简介
第一作者:葛苗苗,女,1988年生,博士,讲师,主要从事非饱和土水力耦合特性及细观结构试验研究。E-mail:gemiaomiao163@163.com;通讯作者:李宁,男,1959年生,博士,教授,主要从事岩体动力学特性的试验研究与裂隙动力学数值仿真模型分析、寒区冻土力学与工程研究的教学和科研工作。E-mail:ningli@xaut.edu.cn。
