摘要
分散土遇水易分散流失,极易对水渠、大坝等水利工程造成冲沟、管涌等危害。为避免陕北地区土石坝因此造成溃坝,采用野外调查分析、经验公式判别、泥球试验和针孔试验,对陕北7座水库10组筑坝黄土的分散性进行了判别,通过土样和库水的物理化学性质分析,阐明了分散土的影响因素及分散机理,同时研究了石灰对分散土的改性作用。分析结果发现,10组筑坝土样中2组属于物理-化学复合性分散土、4组属于低凝聚性土(物理性分散土)、2组属于过渡土、2组属于非分散土。物理-化学复合性分散土在库水的抑制作用下分散性会减弱,表现为低凝聚性土的特征。土体的分散性随着石灰剂量的增加和养护龄期的延长,逐渐降低并完全消除。研究表明,陕北筑坝黄土由于黏粒含量低、钠离子含量高和酸碱度呈碱性,因此具有一定的物理或化学分散性,导致抗水蚀性较差。库水对土的分散性具有较强的抑制作用,石灰对低黏粒含量的分散土有很好的改性效果。
Dispersive soil is easy to disperse and lose when encountering water,which may cause gully,piping and other hazards to water conservancy projects such as canals and dams.In order to avoid dam failure caused by earth rock dams in northern Shaanxi,the dispersity of 10 groups of dammed loess in 7 reservoirs in northern Shaanxi is distinguished by field investigation and analysis,empirical formula discrimination,mud ball test and pinhole test.Through the analysis of physical and chemical properties of soil samples and reservoir water,the influencing factors and dispersive mechanism of dispersive soil are clarified,and the modification effect of lime on dispersive soil is analyzed.The results show that two of the 10 groups of dam soil samples belong to physical-chemical composite dispersive soil,four groups are low cohesion soil(physical dispersive soil),two groups are transitional soil,and two groups are nonDispersive soil.Under the action of reservoir water,the dispersity of physical-chemical composite dispersive soil will be weakened,showing the characteristics of low cohesion soil.With the increase of lime dosage and the extension of curing age,the dispersity of soil gradually decreases,or even completely eliminates.The research shows that the dam loess in northern Shaanxi has certain physical or chemical dispersibility due to its low clay content,high sodium ion content and alkaline p H,resulting in poor water erosion resistance.The reservoir water has strong inhibitory effect on the dispersity of soil,and lime has a good modification effect on the Dispersive soil with low clay content.
作者
任冠洲
李亚军
张蕊
徐铁铮
杜飞
樊恒辉
REN Guanzhou;LI Yajun;ZHANG Rui;XU Tiezheng;DU Fei;FAN Henghui(College of Water Conservancy and Architectural Engineering,Northwest A&F University,Yangling,Shaanxi 712100,China;Shaanxi Province Institute of Water Resources and Electric Power Investigation and Design,Xi’an,Shaanxi 710000,China;Institute of Geotechnical Engineering/Museum of Problematic Rock and Soil,Northwest A&F University,Yangling,Shaanxi 712100,China)
出处
《水利与建筑工程学报》
2022年第4期104-112,共9页
Journal of Water Resources and Architectural Engineering
基金
陕西省水利科技计划项目(2021slkj-19)
国家自然科学基金(52079116)
青年科学基金项目(52108343)。
关键词
黄土
分散性
判别方法
分散机理
改性
loess
dispersity
discrimination method
dispersive mechanism
modification
