冻融循环下盐渍水泥改良风积沙三维力学特性
Three-Dimensional Mechanical Properties of Salinized Cement-Stabilized Aeolian Sand Under Freeze-Thaw Cycles
张少英 1邵帅 1邵生俊 2吴昊 1王泽驰1
作者信息
- 1. 西安理工大学土木建筑工程学院,陕西西安 710048
- 2. 西安理工大学土木建筑工程学院,陕西西安 710048;西安理工大学陕西省黄土力学与工程重点实验室,陕西西安 710048
- 折叠
摘要
为深入研究冻融、盐渍条件下最优水泥含量改良风积沙的三维力学特性与劣化机理,以含盐量分别为0、3％和5％的水泥改良风积沙为研究对象,进行不同冻融循环次数、不同中主应力参数(b值)和不同固结围压的真三轴剪切试验,采用CT技术重建水泥改良风积沙三维孔隙,分析其应力-应变关系、抗剪强度和宏/微观劣化机理.研究结果表明:冻融循环过程中,受盐胀和冻胀作用,沙粒间水泥胶结物的黏结力退化,含盐量越高,试样的抗剪强度降低越显著.重建含盐量为5％的试样在0、3、6、10次冻融循环后的三维孔隙分析认为,孔隙内含盐液体反复冻胀和结晶迁移致使中-小孔隙不断发育,孔隙率由31％增加至37％,连通孔隙率也随之上升,导致冻融循环后抗剪强度降低.Lade-Duncan强度准则破坏参数kf随强度劣化而不断减小,考虑冻融和盐胀耦合作用,采用kf构建强度劣化模型,反映严酷环境、复杂应力条件下改良风积沙强度的劣化度,为沙漠与盐渍地区交通设施地基的建设选材与长期服役性能提供理论参考.
Abstract
In order to investigate the three-dimensional mechanical properties and deterioration mechanisms in aeolian sand stabilized by optimal cement content under freeze-thaw and saline conditions,the cement-improved aeolian sand samples with 0,3％and 5％salt contents were taken as the research object.True triaxial shear tests were performed under different freeze-thaw cycles,intermediate principal stress parameters(b value)and consolidation confining pressures.Using CT technology,three-dimensional pore structures were reconstructed to analyze the stress-strain relationships,shear strength and macro-micro deterioration mechanisms.The results show that freeze-thaw cycles degrade the intergranular cement bonding due to salt expansion and frost heave.As salt content increases,the reduction in shear strength becomes more significant.The three-dimensional pore structures for the specimens with 5％salt content after 0,3,6,and 10 freeze-thaw cycles revealed that the repeated frost heave and water-salt migration resulted in the continuous development in small and medium pores.The porosity increased from 31％to 37％,and the pore connectivity also increased,contributing to the reduction in shear strength after freeze-thaw cycles.Based on the Lade-Duncan strength criterion,the failure parameter kf decreases as strength deteriorates.Considering the combined effect from freeze-thaw cycles and salt expansion,kf was used to establish a strength deterioration model to reflect the strength deterioration degree in cement-stabilized aeolian sand under harsh environments and complex stress conditions.This model provides theoretical guidance for the material selection and long-term service performance transportation evaluation infrastructure in desert and saline regions.
关键词
水泥改良风积沙/冻融循环/真三轴试验/CT扫描试验/三维力学特性/强度劣化模型Key words
cement-stabilized aeolian sand/freeze-thaw cycle/true triaxial test/CT scan/three-dimensional mechanical properties/strength deterioration model引用本文复制引用
出版年
2024
NETL
NSTL
万方数据