滨海细砂路基淤塞机理模型试验  

Experiment on Silting Mechanism of Fine Sand Subgrade in Coastal Area

作　　者：谭鹏 凌建明[2] 钱劲松[2] 曹长伟[1] 李冬雪 

机构地区：[1]中国路桥工程有限责任公司,北京100011 [2]同济大学道路与交通工程教育部重点实验室,上海201804 [3]吉林省交通科学研究所,吉林长春130012

出　　处：《中国公路学报》2017年第11期9-17,共9页China Journal of Highway and Transport

基　　金：财政部专项资金项目(2012MF001)

摘　　要：为了探索滨海地区细砂路基在施工期降雨入渗作用下是否存在淤塞现象,揭示其淤塞机理,自主设计并构建用于验证细砂填料渗流-迁移-淤塞现象的模型试验系统装置;考虑滨海细砂路基砂芯结构的压实状态、湿度状态以及降雨条件等因素,采用模型试验系统装置,研究分别采用细砂和含细粒土细砂这2类细砂路基填料压实成型的砂柱在不同降雨强度和降雨历时下各层位的渗透性、颗粒级配以及湿度变化规律。研究结果表明:在足够大的降雨强度以及相应的降雨历时条件下,入渗水流将引发滨海细砂路基淤塞现象;整个砂柱以及下层砂柱的渗透系数最终呈现出稳定降低的趋势,上层砂柱的渗透系数最终呈现出大致趋于稳定的趋势;砂柱最上层细砂填料细粒组含量的降幅以及砂粒组含量的增幅均为最大,砂柱最底层细砂填料细粒组含量的增幅以及砂粒组含量的降幅最大;各层砂柱的湿度呈现出从上往下增加的规律,并且砂柱中存在明显的干湿分界线;底层细砂填料的持水度明显提高,使得细砂填料的重力排水功能明显降低;细砂路基淤塞宏观上表现为砂芯排水功能衰减以及下层砂芯长时间处于高含水率状态,细观上表现为不同层位细砂粒组的迁移以及迁移的粒组对下层细砂孔隙通道的淤塞作用。In order to explore whether the silting phenomenon objectively existed in the fine sand subgrade,and reveal the silting mechanism of fine sand subgrade in coastal area,a model test system device was independently designed and constructed to verify the seepage-migration-silting phenomenon of fine sand filling.Considering the compaction state,moisture condition and rainfall condition of the sand core structure of fine sand subgrade in coastal area,the model test system device was used to investigate the regularity of the permeability,particle gradation and moisture variation of the sand column,which was respectively compacted with fine sand filling and fine sand filling containing fine grained soil under different rainfall intensity and rainfall duration.The results show that,when the rainfall intensity is large enough and rainfall lasts forsome time,the infiltration flow will trigger fine sand subgrade silting phenomenon.The permeability coefficients of the whole sand column and the lower sand column tend to decrease steadily,and the permeability coefficient of the upper sand column finally tends to be stable.The decrease of fine group content and the increase of sand group content in the top of the sand column reach the peak,whilst the increase of fine group content and the decrease of sand group content in the bottom of the sand column are the largest.The moisture of each layer of sand column increases from the top to the bottom,and there is obvious dry and wet boundary in sand column.The water retention ability of the bottom fine sand filling is obviously improved,thus causing the obvious decrease of the gravity drainage function of fine sand filling.The macroscopic performance of the phenomenon is the decrease of sand core drainage function and the lower sand core for a long time in the high water content state.The micro performance of the phenomenon is the migration of different layers of fine sand grain group and the silting effect of the migration of grain group in the fine pore channel.

关 键 词：道路工程 细砂路基 模型试验 淤塞机理 降雨强度 

分 类 号：U416.1[交通运输工程—道路与铁道工程]