| Civil and Traffic Engineering |
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| Similarity of centrifuge modeling of chloride dispersion in low permeability clay |
| ZENG Xing1,2, ZHAN Liang tong1, ZHONG xiao le3, CHEN Yun min1 |
| 1. MOE Key Laboratory of Soft Soils and Geoenvironmental Engineering, hejiangUniversity, Hangzhou 310058, China;2.School of Civil Engineering, Hunan University of Science and Technology, Xiangtan 411201,China;3. China Construction Installation Engineering Company Limited, Nanjing 210000,China |
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Abstract Kaolin clay and chloride were selected as testing materials for the experimental study on the similitude of dispersion in low permeability clay between centrifuge model and real prototype. Diffusion tests were firstly conducted to determine the relationship between the coefficient of effective diffusion and the void ratio. Then, soil column tests with different values of advection velocity were conducted at 1g and under centrifuge conditions (25g-50g) to obtain the relationship between the coefficient of hydrodynamic dispersion relative to free solution diffusion and Peclet number (Pe). Based on the experimental results, it is found that when Pe is defined based on dispersivity, the previously reported critical Péclet number (Pe=1) can be used for judging similitude of centrifuge modeling ofdispersion in the Kaolin clay. When Pe is defined based on the mean particle size of the clay, the critical Péclet number is much less than 1. When the transport of non reactive pollutant in a 2 m thick low permeability clay liner being subject to a hydraulic head less than 40 mis concerned, the difference between centrifuge modeling with an accelerationless than 100g and real prototype is less than 24%.
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Published: 01 February 2016
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低渗透黏土中氯离子弥散作用离心模拟相似性
针对低渗透黏土中弥散作用离心模拟的相似性问题,以高岭土和氯离子为材料,开展高岭土重塑试样的纯扩散试验,获得氯离子有效扩散系数与孔隙比的关系；在常重力（1g）和超重力（25g~50g）环境下开展不同流速的土柱试验,得到水动力弥散系数与分子扩散系数的比值与Péclet数（Pe）的关系.试验结果分析表明：当Pe基于弥散度定义时,可沿用目前的标准（即Pe=1）判别高岭土中弥散作用的相似性；当Pe基于平均粒径定义时,判别高岭土中弥散作用相似性的临界Pe远小于1.当离心机模拟氯离子击穿2 m厚黏土衬垫时,对于填埋场可能遭遇水头差（0～40 m）,当离心机加速度不高于100g时,击穿时间模拟误差不超过24%.
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