引水灌区黄土地质灾害成因机制与防控技术——以黄河三峡库区甘肃黑方台移民灌区为例  

Formation mechanism as well as prevention and controlling techniques of loess geo-hazards in irrigated areas: A case study of Heifangtai immigration area in the Three Gorges Reservoir of the Yellow River

作　　者：张茂省[1] 

机构地区：[1]国土资源部黄土地质灾害重点实验室/中国地质调查局西安地质调查中心,陕西西安710054

出　　处：《地质通报》2013年第6期833-839,共7页Geological Bulletin of China

基　　金：中国地质调查局项目(编号:1212011014024);国家科技支撑计划课题(编号:2012BAK10B02)

摘　　要：黄土是具有水敏性的特殊类土,遇水后性质发生明显变化,甚至引发地质灾害。甘肃黑方台地区由于引水灌溉引发的滑坡和黄土湿陷等灾害十分严重,也很典型,已成为地质灾害研究和工程实践的热点地区之一。针对引水灌区黄土地质灾害成因机制研究与防控技术中存在的问题,以黑方台地区为例,从灌溉水入渗引起的地下水动力场与黄土工程地质性质响应及其诱发的黄土滑坡和黄土湿陷灾害等方面开展了国际合作研究。研究表明,40余年引水灌溉导致台塬中心部位地下水位上升了20m,升幅为0.476m/a,导致滑坡灾害频发,平均每年发生3～4次,引起黄土湿陷总量达5.9m,非饱和黄土和湿陷系数小于0.015的黄土所引起的湿陷量达到2.16m,对黄土湿陷性研究提出新的挑战。灌区地质灾害风险防控的关键是改变灌溉模式,减少地下水补给,实施排水工程,有效地降低斜坡地带的地下水位。Loess is a special type of soil with water sensitivity. The engineering properties of loess change dramatically after soaking with water, which can even cause geo-hazards. Due to irrigation, geo-hazards such as landslides and collapses in Heifangtai are both very severe and typical. Hence Heifangtai has become one of the hot spots for geo-hazard researches and engineering applications. Heifangtai was taken as a study case to reveal the formation mechanism as well as prevention and controlling techniques of loess geo-hazards in irrigation areas. International cooperation researches were carried out in the aspects of hydro-dynamic field and loess engineering geological property responses to irrigation infiltration as well as the consequent loess landslides and loess collapses. The results show that, after 40 years of irrigation, the groundwater table in the center of the plateau has been elevated by 20m with an annual rise of 0.476m. This has led to frequent landslides with annual frequency up to 3 to 5 times. Also, irrigation results in a total collapse of loess of 5.9m. Collapses belonging to both unsaturated loess and loess with a collapse coefficient less than 0.015 reach 2.16m. This has constituted new challenges to the researches on loess collapsibility. The keys to risk control measures of geo-hazards in irrigation areas include changes of irrigation mode, reduction of the recharge of groundwater and implementation of drainage projects to lower groundwater table near the slopes.

关 键 词：滑坡 水敏性 黄土湿陷 风险控制 

分 类 号：P642.131[天文地球—工程地质学] P642.22[天文地球—地质矿产勘探]