摘要
[目的]模拟酸雨对红黏土抗剪强度特征的影响,并结合酸雨侵蚀后红黏土的微结构,分析影响强度机理,为酸雨区的基础设施建设特别是路基边坡防护和保障基础设施安全运营提供理论和工程指导。[方法]以云南省昆明市某路基边坡红黏土为研究对象,采用静态浸泡试验,用纯水和配置不同浓度的酸液对红黏土进行7,14和28 d的浸泡和侵蚀,然后采用直剪试验对红黏土的抗剪强度进行测定,同时采用电镜扫描和能谱分析对侵蚀以后土样的微观结构进行解析以此来开展侵蚀机理研究。[结果]①酸液对红黏土应力应变特征影响是明显的,特别是在高浓度酸液的侵蚀下,应力应变曲线变得不稳定,呈台阶上升状,具有应变硬化特征。②受酸液的侵蚀影响,红黏土的抗剪强度最高降低率可达到70%(7 d)和80%(14 d),在pH值为0的高浓度酸液侵蚀28 d以后,抗剪强度仅有5 kPa左右,强度基本完全损失;同时在高浓度酸液侵蚀下,不论侵蚀多长时间,黏聚力都最低,仅为4.99,2.19,0.02 kPa。随着浸泡时间和酸液浓度的增加,红黏土的抗剪强度指标黏聚力和内摩擦角均逐渐降低,且酸液浓度对强度及其指标的影响更为显著。③酸液导致倍半氧化物减少,粒间黏结性和黏结力降低,内部孔隙增大结构疏松,含水率增大是红黏土抗剪强度和黏聚力降低的原因,而酸液使粒径整体减小是内摩擦角降低的主要原因。[结论]酸雨对红黏土路基边坡红黏土强度影响明显,酸雨浓度比降雨时长对强度影响更为显著,在路基边坡稳定性的预测与防治及保障公路基础设施安全运营时应予以重视。
[Objective]The effect of simulated acid rain on the shear strength characteristics of red clay was investigated and the influence strength mechanism and microstructure of red clay after acid rain corrosion was analyzed in order to provide theoretical and engineering guidance for the construction of infrastructure in acid rain area,especially the protection of roadbed slope and safe operation of infrastructure.[Methods]The red clay of a roadbed slope in Kunming City,Yunnan Province was used as the research object.The study adopted the static soaking test and used pure water and acid liquor with different concentrations to soak and erode the red clay for 7,14,and 28 days.Thereafter,the shear strength of the red clay was measured using the direct shear tests,and the microstructures of the eroded soil samples were analyzed via electron microscope scanning and energy spectrum analysis to analyze the influence mechanism of strength.[Results]①The effect of acid liquor on the stress-strain characteristics of red clay is significant,especially under high concentration acid.The stress-strain curve was unstable and increased like a step,with strain hardening characteristics.②With the increase in soaking time and acid concentration,the shear strength of red clay and its index of cohesion and internal friction angle gradually decreased,and the acid concentration had a more significant effect on the strength and its index.③Acid liquor decreased the sequioxide and the interparticle adhesion and bonding force and simultaneously increased the internal pores,loosened the structure,and increased the soil moisture content,thereby resulting in a decrease in shear strength and cohesion;however,the overall decrease in particle size caused by acid was the main reason for the decrease in the internal friction angle.[Conclusion]Acid rain has a significant effect on the strength of red clay from roadbed slope,and the intensity of acid rain has a more significant effect on the strength than the duration of rainfall.Attention should be
作者
钱春华
Qian Chunhua(Kunming Survey and Design Institute of State Forestry Administration,Kunming,Yunnan 650000,China)
出处
《水土保持通报》
CSCD
北大核心
2024年第5期10-18,27,共10页
Bulletin of Soil and Water Conservation
基金
芒市公路投资有限公司项目“云南省德宏州芒瑞大道建设”。
关键词
红黏土
酸雨侵蚀
静态浸泡试验
抗剪强度
red clay
acid rain corrosion
static soaking test
shear strength
