滤网孔径和层数对反滤保土效果的影响分析  

Influence of pore size and filter layers on soil retentioneffect

作　　者：段国军 张顺福[2,3] 介玉新[1] DUAN Guojun;ZHANG Shunfu;JIE Yuxin(State Key Laboratory of Hydroscience and Engineering,Tsinghua University,Beijing 100084,China;China Institute of Water Resources and Hydropower Research,Beijing 100038,China;Research Center on Flood&Drought Disaster Reduction of the Ministry of Water Resources,Beijing 100038,China)

机构地区：[1]清华大学水沙科学与水利水电工程国家重点实验室,北京100084 [2]中国水利水电科学研究院,北京100038 [3]水利部防洪抗旱减灾工程技术研究中心,北京100038

出　　处：《水利水电技术》2020年第1期39-45,共7页Water Resources and Hydropower Engineering

基　　金：国家“十三五”重点研发计划(2017YFC1502602);国家自然科学基金项目(41790434)

摘　　要：针对土工织物反滤层的反滤保土性问题,采用滤网代替土工织物的孔隙,利用颗粒流程序对无黏性基土-滤层的反滤过程进行二维离散元数值模拟。依次研究了单孔、单层和多层滤网在不同孔径比O/d下的反滤保土效果。对比不同孔径比O/d下反滤稳定后的基土颗粒形态,绘制反滤稳定的力链图,分析颗粒间接触力的分布,从细观上解释滤层保土性的原因,进一步计算颗粒流失率,分析滤层孔径及层数对保土性的影响规律。结果表明:孔隙附近颗粒成拱是滤层发挥保土性的原因,孔径比O/d过大会降低颗粒拱的稳定性导致保土性下降;颗粒间接触力的分布细观上验证了颗粒的拱效应,多层滤网层间截留颗粒仍可与滤网一同增加滤层的保土性;滤层孔径较大时,增加滤网层数能够在一定程度上弥补保土能力的不足。Aiming at the problem of soil retention of geotextile filter layer,regular filter nets were used to simulate geotextile in studying the filtration process in cohesionless soil-filter system based on particle flow program.The filtration effect was investigated for a single filter pore,a single filter net and multilayer filters with different ratios of pore diameter to the diameter of soil particle(O/d).By comparing the stable soil skeleton and the force chains between stable particles after filtration to analyze the distribution of contact force between particles,the paper discusses the mechanism for the soil retention of the filter layer from a mesoscopic view.The optimal value of O/d and filter layers were also estimated by computing the loss ratio of particles for different type of filters.Results indicate that the arching effect of particles near the filter pores is the main cause for soil retention,too large O/d will reduce the stability of the particle arch,resulting in a decrease in soil retention,interlayer particles can still increase the soil retention capacity of the filter layer together with the filter screen,which are verified by force chains.It is also found that increasing the number of layers can,to some extent,make up the shortage in soil retention effect for filters with large pores.

关 键 词：反滤 保土 孔径 力链 管涌 基土流失率 渗流 稳定性 

分 类 号：TV640.33[水利工程—水利水电工程]