首页 | 本学科首页   官方微博 | 高级检索  
     检索      


Permeability and sedimentation characteristics of pleistocene fluvio-glacial deposits in the Dadu river valley, Southwest China
Authors:Guo-xiang Tu  Run-qiu Huang  Hui Deng  Yan-rong Li
Institution:1. State Key Laboratory of Geo-hazard Prevention and Geo-environment Protection, Chengdu University of Technology, Chengdu, 610059, China
2. Department of Earth Sciences, The University of Hong Kong, Hong Kong, China
Abstract:There exist many fluvio-glacial deposits in the valley of Dadu River, Southwest China, which dates back to the Pleistocene. As some of the deposits are located within the seasonal water fluctuation zone of reservoirs, the seepage of groundwater acts as one of the key factors influencing their stability. Investigation into the sediment properties and permeability is, therefore, crucial for evaluating the sediment stability. In this study, in-situ permeability and sieving tests have been carried out to determine grain size distribution, correlations of permeability and hydraulic gradients, and relations between permeability and sedimentation properties. Test results indicate that the deposits are composed mostly of sands, gravels, cobbles and boulders, and the percentage of fines is less than 5%. The sediments have high densities, low porosities and natural moisture contents. At low hydraulic gradients, the seepage velocity obeys the Darcy’s law, while a non-Darcy permeability is observed with hydraulic gradient exceeding a certain value (about 0.5–0.7). The linear permeability coefficient ranges from 0.003 to 0.009 cm/s. Seepage failure occurs above a threshold between 1.1 and 1.5. The test data fit well with the non-linear permeability equations suggested by Forchheimer and Izbash. The non-Darcy permeability proves to be in accordance with the seepage equation suggested by Izbash with the power ‘m’ of about 0.6–0.7. The characteristic grain sizes of the studied deposits are found in a narrow range between 0.024 and 0.031 mm, which is much lower than the effective grain size (d 10).
Keywords:
本文献已被 CNKI SpringerLink 等数据库收录!
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号