摘要
在季节性冻土区域对路基土进行改良是一种较常用的工程措施,木质素纤维是一种经济环保,且具有良好耐久性的添加材料。以木质素纤维改良土为研究对象,对经历冻融循环后不同木质素纤维掺入量的改良土样进行UU三轴试验和SEM电镜扫描试验,着重分析了冻融次数和纤维掺量对改良土力学性质的影响规律。结果显示:应力应变曲线特性与围压、冻融次数、木质素纤维掺量均有较大关系。改良土的弹性模量、强度、黏聚力等都随着冻融循环次数的增加而降低;0.75%掺量的木质素纤维改良土弹性模量、强度、黏聚力均最大,且冻融次数越多,其表现出的强度优势越大。纤维在土样内部形成了三维网架结构或是起到了"桥梁"搭接作用,减小了冻融对土体微观孔隙损伤的影响,从而增强了土体的强度。试验研究表明,木质素纤维改良土在抵抗反复冻融问题上具有明显的优势。
It is a common engineering method to improve the subgrade soils in seasonal frozen soil areas.Lignin fiber is an economical and environmentally friendly additive with good durability.Taking the soils improved by the lignin fiber as the research object,the UU triaxial tests and SEM scanning tests are carried out on the soil samples with different contents of lignin fiber after freeze-thaw cycles.The influences of the times of freeze-thaw cycles and the content of fiber on the mechanical properties of the soils are analyzed emphatically.The results show that the characteristics of stress-strain curve are related to confining pressure,freeze-thaw times and lignin fiber content.The elastic modulus,strength and cohesion of the reinforced soils decrease with the increase of freeze-thaw cycles.Under the lignin fiber content of 0.75%,the elastic modulus,strength and cohesion of the reinforced soils reach the maximum.The fiber forms a three-dimensional grid structure in the soil samples or plays a role of"bridge"overlapping,which reduces the impact of freeze-thaw on the pore damage,thus enhancing the strength of the soils.The test results show that the reinforced soils with lignin fiber have obvious advantages in resisting repeated freeze-thaw cycles.
作者
陈诚
郭伟
任宇晓
CHEN Cheng;GUO Wei;REN Yu-xiao(State Key Laboratory of Hydraulic Engineering Simulation and Safety,Tianjin 300072,China;Department of Architectural Engineering,Tianjin University,Tianjin 300072,China)
出处
《岩土工程学报》
EI
CAS
CSCD
北大核心
2020年第S02期135-140,共6页
Chinese Journal of Geotechnical Engineering
基金
国家自然科学基金项目(51878446)
天津市自然科学基金项目(18JCYBJC40500)
关键词
冻融循环
木质素纤维改良土
力学性质
电镜扫描
freeze-thaw cycle
lignin fiber-reinforced soil
mechanical property
scanning electron microscopy
