摘要
有机质含量和组分的变化往往造成土体力学性质的差异。为研究泥炭土或有机质土在三维受力下的剪切强度特性并分析引起力学差异性的原因,本文在马来西亚东海岸铁路沿线选取数组有机质土、泥炭土试样开展三轴固结不排水(Consolidated Undrained,CU)、三轴不固结不排水(Uncosolidated Undrained,UU)及微观电镜(Scanning Electron Microscopy,SEM)试验,并对两类土的微观结构展开分析,探讨有机质对土体力学性质的影响机制。试验结果表明:CU试验时,有效内摩擦角和黏聚力与有机质含量成负相关;UU试验时,随有机质含量增加黏聚力呈指数降低。直接原因是有机质土中残余纤维的牵拉作用以及泥炭土中腐殖质的润滑作用。在剪切过程中,泥炭土表现为先剪胀后剪缩,应变曲线先硬化后趋稳;有机质土应变线型普遍为软化型,且软化程度在有机质含量5%左右最剧烈。马来西亚地区泥炭土和有机质土所含有机质种类不同,前者以腐殖质团聚体为主,后者以残余纤维为主,造成二者抗剪能力存在差异。
Changes in the content and composition of organic matter often lead to differences in the mechanical properties of soil.In order to explore the shear strength characteristics of peat soil or organic soil under three-dimensional forces and analyze the causes of mechanical differences,In this paper,triaxial consolidated undrained(CU),triaxial unconsolidated undrained(UU)and microscopic electron microscope(SEM)tests were carried out on an array of Malaysian organic soil and peat samples along the East Coast Railway in Malaysia,and the influence mechanism of organic matter on soil mechanical properties was discussed by analyzing the microstructure of the two types of soil.The results show that the effective internal friction angle and cohesion are negatively correlated with the content of organic matter in CU test.During the UU test,the organic matter content increased,but the cohesion decreased exponentially.The direct cause of this result is the pulling effect of residual fibers in organic soil and the lubrication effect of humus in peat soil.During the shearing process,the peat first dilates and then shrinks,and the stress-strain curve first hardens and then becomes stable.The stress-strain curve of organic soil is generally softening type,and the softening degree is most severe when the content of organic matter is about 5%.The types of organic matter in peat soil and organic soil in Malaysia are different.The former is dominated by humus aggregates,while the latter is dominated by residual fibers,resulting in a great difference in shear resistance.
作者
张莹晨
黄晶
沈宇鹏
李志强
ZHANG Yingchen;HUANG Jing;SHEN Yupeng;LI Zhiqiang(School of Civil Engineering,Beijing Jiaotong University,Beijing 100044,China;CCCC China Harbour Engineering Co.Ltd.,Beijing 100027,China;China Academy of Transportation Science,Beijing 100029,China)
出处
《铁道建筑》
北大核心
2025年第6期164-171,共8页
Railway Engineering
基金
中国交通建设集团有限公司重点研发项目(2021-ZJKJ-18)。
关键词
铁路路基
抗剪强度
试验研究
泥炭土
有机质土
railway subgrade
shear strength
experimental research
peat
organic soil
作者简介
第一作者:张莹晨(2001-),女,硕士研究生。E-mail:2329010499@qq.com;通信作者:沈宇鹏(1977-),男,教授,博士。E-mail:ypshen@bjtu.edu.cn。
