深埋冰水堆积地层高压大型潜蚀试验研究  

Large scale high-pressure internal erosion tests on a deeply buried glacial deposit

作　　者：张争 廖明可 张博[1] 王伟博 王刚[2] Zhang Zheng;Liao Mingke;Zhang Bo;Wang Weibo;Wang Gang(POWERCHINA Northwest Engineering Corporation Limited,Xi′an 710065,China;School of Civil Engineering,Chongqing University,Chongqing 400045,China)

机构地区：[1]中国电建集团西北勘测设计研究院有限公司,西安710065 [2]重庆大学土木工程学院,重庆400045

出　　处：《工程勘察》2024年第9期36-43,共8页Geotechnical Investigation & Surveying

基　　金：国家自然科学基金(52079012)。

摘　　要：冰水堆积体粒径跨度大、级配不连续,在渗流作用下易发生潜蚀现象。采用自行研发的大型粗粒土压缩渗透试验仪,对某水电工程深埋冰水堆积体开展了高竖向压力下的潜蚀试验,得到了试样的细粒流失率、渗透系数和体积变形随水力梯度的变化过程。试验结果表明,不同缩尺方法对试样的潜蚀特性影响显著,剔除法和相似级配法不仅会低估试样的渗透性,还会高估试样的内部稳定性。等量替代法级配和缺乏中间粒径的危险级配试样在较低的水力梯度下即会发生显著的细粒流失,导致渗透系数突变和体积变形。竖向压力对临界和破坏水力梯度、渗透系数、细粒流失率和体变的发展过程均有影响,影响程度与颗粒级配有关。即使在2MPa的高竖向压力下,等量替代法级配和危险级配仍具有较高的细粒流失率,表明该深埋覆盖层具有较高的潜蚀风险。The glacial gravelly deposit is susceptible to internal erosion due to its wide and gap gradation.Internal erosion tests on a glacial gravel deeply buried in the dam site of a hydropower project were conducted using a recently-invented large-scale compression and seepage apparatus.The change of eroded fine particlemass,permeability and volumetric deformation of the specimens with the imposed hydraulic gradient were obtained.The test results show that different specimen scaling methods have significant effects on the suffusion characteristics of the soil.Simply removing the oversize particles or scaling-down the overall particle sizes not only underestimated the permeability of the specimens,but also overestimated the internal stability of the specimens.According to the test results of the equivalent-mass substitution gradation and the gap-graded dangerous gradation,the soil can exhibit significant fine particle loss at relatively low hydraulic gradients,leading to remarkable changes in permeability and volumetric deformation.Surcharge pressure has a considerable effect on the critical and failure hydraulic gradients,as well as on the development of the permeability coefficient,the fine particle loss,and the volumetric deformation.The influencing extent of the surcharge pressure depends on particle gradation.Both for the equivalent-mass substitution gradation and the gap-graded dangerous gradation,the specimens still exhibited high fine-grain loss rates even at a high vertical pressure of 2MPa,indicating that the deep buried alluvium has a high risk of internal erosion.

关 键 词：冰水堆积覆盖层 潜蚀 细粒流失 水力梯度 竖向压力 

分 类 号：TU443[建筑科学—岩土工程]