摘要
工程中经常出现因水力梯度、土体细粒含量、反滤层渗透性变化等因素导致的机械淤堵问题。为探究不同因素作用下土-土工织物反滤体系渗透淤堵机理,对现有规范中的梯度比GR试验装置进行改进并补充试验方法,开展了3种水力梯度、3种细粒含量、4种土工织物规格条件下的渗透试验。试验结果表明:改进后的梯度比GR试验仪结合补充的试验方法可以区分土工织物淤堵和土体自身“淤堵”;土-土工织物反滤体系的渗透性与细粒含量、织物单位面积质量成反比,与水力梯度成正比;通过二次筛分,发现土体细粒含量较多的土样在高水头作用下会在土体内部形成可以截住细粒的天然滤层,导致天然滤层上方土体出现淤堵现象,而靠近织物土层的细粒在渗透水流作用下移向或逸出土工织物,造成梯度比GR和渗透系数均下降,通过增加织物孔径能降低土体的淤堵程度,提高反滤体系透水能力。分析结果进一步表明,通过改进的淤堵试验仪以及二次筛分试验可以合理地评价土工织物反滤体系的淤堵范围和淤堵程度,为工程中判断反滤体系的渗透淤堵特性提供参考。
As the problem of the mechanical clogging caused by hydraulic gradient, fine particle content of soil mass and change of permeability of filter layer often occurs in the relevant engineering project, and then the gradient ratio GR test device specified in the related existing specification is improved along with the supplementation of the experiment method, while the permeability experiments are carried out under the conditions of three hydraulic gradients, three fine soil contents and four specifications of geotextile, so as to explore the infiltration clogging mechanism of soil-geotextile filtration system under different factors. The experimental results show that combined with the supplemented experiment method, the improved GR tester can distinguish both the clogging from geotextile and the clogging from soil mass itself. The permeability of the soil-geotextile filtration system is inversely proportional to the fine grain content and the mass per unit area of the geotextile and is proportional to the hydraulic gradient. Through secondary screening, it is found out that the soil sample with more fine particles is to form a natural filter layer that can intercept fine particles under the effect of high water head, which can lead to occurrence of a clogging phenomenon, while the fine particles near the geotextile soil layer move towards or escape from the geotextile under the effect of seepage flow and then cause the decreases of both gradient ratio GR and the permeability coefficient. Through increasing the pore size, the clogging degree of soil mass can be decreased and the pervious capacity of the filtration system can be improved as well. The analysis results further indicate that the clogging range and clogging degree of the geotextile filtration system can be reasonably assessed through the improved clogging tester for providing relevant references to estimate the infiltration clogging characteristics of the filtration system in actual engineering project.
作者
吕从聪
刘名广
卢晓春
王玉杰
孙兴松
LYU Congcong;LIU Mingguang;LU Xiaochun;WANG Yujie;SUN Xingsong(Hubei Key Laboratory of Hydropower Engineering Construction and Management,China Three Gorges University,Yichang 443002,Hubei,China;College of Hydraulic and Environmental Engineering,China Three Gorges University,Yichang 443002,Hubei,China;Geotechnical Engineering Institute,China Institute of Water Resources and Hydropower Research,Beijing 100038,China)
出处
《水利水电技术（中英文）》
北大核心
2022年第12期47-55,共9页
Water Resources and Hydropower Engineering
基金
新疆水利科技专项资金项目(XSKJ-2022-05)
国家重点研发计划(2018YFC0407000)
湖北省水电工程施工与管理重点实验室(三峡大学)开放基金(2020KSD13)。
关键词
土-土工织物反滤体系
渗透淤堵机理
影响因素
梯度比GR试验
二次筛分
soil-geotextile filtration system
infiltration clogging mechanism
impacting factors
gradient ratio GR experiment
secondary screening
