桂东南容县非饱和花岗岩风化土的土水特征  

Soil-water characteristic of unsaturated granite weathered soil in Rong county,Southeast Guangxi province

作　　者：赵瑞华 韦文智 廖丽萍[1,2,3] 文海涛 杨云川 许英姿[1,2,3] ZHAO Ruihua;WEI Wenzhi;LIAO Liping;WEN Haitao;YANG Yunchuan;XU Yingzi(College of Civil Engineering and Architecture, Guangxi University, 530004,Nanning, China;Key Laboratory of Disaster Prevention and Structural Safety of Ministry of Education, Guangxi University, 530004, Nanning, China;Guangxi Key Laboratory of Disaster Prevention and Engineering Safety, Guangxi University, 530004, Nanning, China;Guangxi Zhuang Autonomous Region Geological Environment Monitoring Station, 530028, Nanning, China)

机构地区：[1]广西大学土木建筑工程学院,南宁530004 [2]工程防灾与结构安全教育部重点实验室,南宁530004 [3]广西防灾减灾与工程安全重点实验室,南宁530004 [4]广西壮族自治区地质环境监测站,南宁530028

出　　处：《中国水土保持科学》2022年第2期24-33,共10页Science of Soil and Water Conservation

基　　金：国家自然科学基金“花岗岩残积土降雨滑坡起动过程剪胀效应及其临界灾变机制研究”(41901132);广西自然科学基金“桂东南花岗岩残积土滑坡土水作用力学机制”(2021GXNSFBA220025)。

摘　　要：崩岗与滑坡在桂东南容县花岗岩风化土层中频繁发生,危害严重。风化土的土水特征与相对渗透系数不仅是非饱和渗流计算的重要依据,也是研究崩岗侵蚀过程与机理、滑坡形成的必要基础。开展筛分试验和压汞试验分别获得花岗岩风化土的颗粒级配累积曲线及孔径分布曲线,采用压力膜仪进行脱湿试验,研究各初始干密度花岗岩风化土的土水特征,分析Van Genuchten、Gardner、Brook&Corey模型的适用性,预测非饱和风化土的相对渗透系数及探讨渗透系数的差异。结果表明:残积土与全风化土土水特征曲线均呈现“双台阶”特征,且优势孔隙为集聚体间孔隙和颗粒间孔隙;然而,初始干密度对残积土脱湿过程的影响较全风化土显著。同一干密度全风化土的孔径分布系数较残积土的大,而孔径分界点却较残积土的小。Van Genuchten与Gardner模型对2种土的适用性均最好(R^(2)>0.93),Brook&Corey模型适用性次之。残积土相对渗透系数与渗透系数均随干密度的增大而减小,且较全风化土的小。容县花岗岩风化土边坡上弱下强的不均匀渗透特性与其粒度组成有关,并影响边坡变形破坏模式与崩岗侵蚀特征。[Background]Collapsing hills and landslides frequently break out in the granite weathered soil in Rong county,Southeast Guangxi,causing serious damage.The soil-water characteristics and relative permeability coefficients of weathered soil are not only an important basis for unsaturated seepage calculations,but also a necessary basis for the erosion process and mechanism of collapsing hills and landslides formation.[Methods]In this paper,the curve of particle gradation accumulation and the pore size distribution was obtained by using sieving test and mercury intrusion test respectively.In addition,the pressure film instrument was used to carry out the dehumidification test to study the soil-water characteristics of the granite weathered soil with different initial dry densities.Then the applicability of Van Genuchten,Gardner and Brook&Corey model was analyzed.Finally,the relative permeability coefficients of unsaturated weathered soil were predicted by using Van Genuchten and Gardner model,and the differences were explored by comparing the permeability coefficients of granite residual soil and fully weathered soil.[Results]The soil-water characteristic curves of residual soil and fully weathered soil both presented a“double-step”feature,and the dominant pores were inter-aggregate pores and inter-particle pores.However,the effect of initial dry density on the dehydration process of residual soil was more significant than that of fully weathered soil.Though the pore distribution coefficient of fully weathered soil was larger than that of residual soil,the pore size dividing point was smaller than that of residual soil with the same dry density.The applicability of the Van Genuchten and Gardner models to the two soils was the best(R^(2)>0.93),and the applicability of the Brook&Corey model was second.The relative permeability coefficient and permeability coefficient of residual soil both decreased with the increase of dry density,and were smaller than those of fully weathered soil.[Conclusions]The granite weathere

关 键 词：非饱和花岗岩风化土 土水特征 相对渗透系数差异 桂东南容县 

分 类 号：S157[农业科学—土壤学]