水利大坝施工围堰建设中,常采用水下抛填。砂、砂砾石及石碴等散粒料常被用作抛填材料,其水下抛填密度是围堰设计中的关键指标。由于散粒料水下抛填后很难直接取样测定其密度,目前也没有成熟的理论计算方法,抛填后堰体密度的确定成为困扰围堰设计和施工的难题。在分析抛填堰体密度影响因素的基础上,针对工程中应用的砂、砂砾石及石碴3种典型散粒料,设计进行了多组离心模型试验,测得了散粒料水下抛填密度,研究了颗粒形状、大小和级配等因素对水下抛填密度的影响。基于离心模型试验成果,提出了散粒体水下抛填堰体密度的估算公式,可供水下抛填围堰设计和施工参考。
Abstract
Before building a dam in a river, cofferdams are needed to be constructed in advance. The most commonly used method of filling a cofferdam is to dump granular materials into the deep water and let the particles pack together by gravity. Granular materials such as sand, sandy gravel and ballast are often used as the main packing materials, and the density formed by underwater packing of granular material is the key parameter for cofferdam design. Since the density cannot be obtained directly by sampling or calculation owing to the lack of theoretical or empirical solution, it has become an unsolved problem in the design and construction of cofferdam. In view of this, through analyzing the density’s influencing factors we conducted centrifugal model tests on 3 typical granular materials (sand, sandy gravel, and ballast) to measure the densities under different conditions, and investigated the influences of particle figuration, size and gradation on the density. On the basis of the test data, some insights about the particle packing underwater are summarized, and a tentative formula to estimate the particle aggregate density is proposed.
关键词
散粒料 /
围堰 /
密度 /
离心模型试验
Key words
granular material /
cofferdam /
density /
centrifugal model test
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基金
“十二五”国家科技支撑计划项目(2008BAB29B02);中央级公益性科研院所基本科研业务费项目(CKSF2010015)
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