摘要
重塑黄土抗剪强度对黄土重大工程的长期稳定与安全有着极其重要的影响,然而,由于传统测试方法的限制,对于结合水与抗剪强度之间关系的认识并不充分。本文基于无损、可靠、精确与便捷的核磁共振技术,针对不同含水率的重塑黄土开展了结合水发育特征与重塑黄土抗剪强度的试验研究。利用结合水与自由水的冰点不同,寻找二者的核磁共振信号界限—T2截止值,然后获取不同含水量直剪试样的核磁共振驰豫曲线,最后结合快剪试验分析结合水含量与土体抗剪强度的关系。试验结果表明:(1)重塑黄土内结合水含量随含水量的上升而增多,且增长趋势逐渐变缓,结合水所占比例也在不断地下降。(2)当土体内含水量增大时,并不会单独发育某一赋存状态的水,而是在某个含水率区间内主要发育某一种赋存状态的水。(3)重塑黄土中结合水的增加会导致粘聚力的降低,对内摩擦角没有明显影响。重塑黄土试样内结合水主要是通过削弱土体的粘聚力从而降低黄土土体抗剪强度,且土体内结合水含量与粘聚力c值及抗剪强度大小呈线性负相关。本文研究成果可为非饱和黄土边坡与高填方工程的稳定性计算等方面提供技术支持与理论参考。
Shear strength of remolded loess has a close connection with the stability and safety of major engineering projects in loess areas.Due to limitation of traditional testing methods,development characteristics of bound water and its influence on shear strength of loess were not clearly understood.In this study it performed some trials on loess based on reliable,accurate and convenient nuclear magnetic resonance(NMR)technique.In terms of the property of remolded loess,it firstly found boundary between combined water and free water according to the differences in their freezing points.Then the NMR relaxation curves of direct shear samples were obtained so as to determine the content of bound water as well as the relationship between content of bound water and shear strength of loess.The results show that:(1)Content of bound water in remolded loess increased with the addition of water content;(2)When the water content of soil body increased,the bound water or free water didn't vary independently;in case one dominate,and the other still exist in small quantities;(3)Increase of combined water content leaded to the decrease of cohesion in remolded loess,but the angle of internal friction did not change significantly,and the content of combined water was negatively correlated with c value and shear strength.This research results can provide technical support and theoretical reference for unsaturated loess slope construction and filling engineering.
作者
何攀
许强
刘佳良
蒲川豪
陈达
HE Pan;XU Qiang;LIU Jialiang;PU Chuanhao;CHEN Da(State Key Laboratory of Geohazard Prevention and Geoenvironment Protection, Chengdu University of Technology,Chengdu 610059, China)
出处
《山地学报》
CSCD
北大核心
2020年第4期571-580,共10页
Mountain Research
基金
国家自然科学基金重大项目(41790445)
国家自然科学基金重点项目(41630640)。
