| 砂性地层中盾构泥浆粗粒材料对成膜效果的影响 |
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| 引用本文： | 刘成,陆杨,吕伟华,刘磊. 砂性地层中盾构泥浆粗粒材料对成膜效果的影响[J]. 中国公路学报, 2018, 31(9): 104-111 |
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| 作者姓名： | 刘成 陆杨 吕伟华 刘磊 |
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| 作者单位： | 1. 南京林业大学 土木工程学院, 江苏 南京 210037;2. 河海大学 岩土力学与堤坝工程教育部重点实验室, 江苏 南京 210098 |
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| 基金项目： | 国家自然科学基金项目（51508278，51508279）；江苏省自然科学基金项目（BK20140979，BK20150885）；岩土力学与堤坝工程教育部重点实验室开放基金项目（GH201402） |
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| 摘 要： | 为了解决泥水盾构工程中高透水地层开挖面上泥膜形成困难的问题，从改善泥浆成膜性能的角度出发，在泥浆中添加轻质砂作为粗粒材料，开展加砂泥浆在砂性地层中的渗透成膜试验研究。改变泥浆中粗粒材料的粒径和添加量，测定不同加载条件下的成膜滤失量。根据成膜时间和冲破压力等成膜指标，分析粗粒材料对泥膜形成效果和修复能力的影响，探明加砂泥浆的成膜空间分布特征，揭示粗粒材料在不同孔隙尺寸的砂性地层中的堵塞机制。结果表明：泥浆粗粒材料可有效堵塞地层孔隙并提高成膜效率，提高泥膜冲破压力和修复能力；泥膜形成区域可以分为前端扩散区、初始形成区及后端形成区，初始形成区和后端形成区的泥膜承担了大部分水土压力；粗粒材料粒径与地层孔隙直径的比值关系决定了初始形成区的分布区域、分布形态及发展方向；粒径较小的粗粒材料（0.3 mm或0.5 mm）与泥浆颗粒能产生良好的协同作用，形成稳定的架桥结构，泥膜更为致密，质量较好；而添加粒径较大的粗粒材料（0.75 mm或1.0 mm）将产生较大的滤失量，或者难以形成泥膜；加砂泥浆的成膜效率随着粗粒材料添加量的增加而大幅提高，但添加量增加到一定程度后，这种提升效果显著减弱。特定粒径的粗粒材料具有一定的适用范围，因此需要根据地层孔隙特征合理选取粗粒材料的粒径和添加量以达到最佳的成膜效果。
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| 关 键 词： | 隧道工程 成膜效果 模型试验 加砂泥浆 泥水盾构 砂性地层 |
| 收稿时间： | 2017-10-15 |
Effects of Coarse-particle Materials in Slurry on Filter-cake Formation Effectiveness in Sandy Strata |
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| LIU Cheng,LU Yang,LYU Wei-hua,LIU Lei. Effects of Coarse-particle Materials in Slurry on Filter-cake Formation Effectiveness in Sandy Strata[J]. China Journal of Highway and Transport, 2018, 31(9): 104-111 |
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| Authors: | LIU Cheng LU Yang LYU Wei-hua LIU Lei |
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| Affiliation: | 1. School of Civil Engineering, Nanjing Forestry University, Nanjing 210037, Jiangsu, China;2. Key Laboratory of Ministry of Education for Geomechanics and Embankment Engineering, Hohai University, Nanjing 210098, Jiangsu, China |
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| Abstract: | To solve the problem of filter-cake formation on the excavation face of high permeable strata for slurry shield projects, from the perspective of improving the filter-cake formation performance, light sands used as coarse-particle materials were added into the slurry, and an experimental study on slurry infiltration and filter-cake formation in sandy strata was conducted. By changing the particle diameters and additive contents of coarse-particle materials, the filtrate mass under different loading conditions was measured. According to the indexes of filter-cake formation such as the formation time and breaking pressure, the influences of coarse-particle materials on the formation effectiveness and recovery capability of filter-cake were analyzed. The spatial distribution characteristic of filter-cake formation was studied for slurry containing coarse-particle materials, and the clogging mechanism of coarse-particle materials in sandy strata with different pore characteristics was revealed. The results indicate that the coarse-particle materials in slurry can effectively clog the strata pores and improve the formation effectiveness of filter-cake. It can also increase the breaking pressure and improve the recovery capability of filter-cake. The formation zone of filter-cake can be divided into the front diffusion zone, initial formation zone, and back formation zone. The filter-cake in the initial formation zone and back formation zone bears most of the earth and water pressure. The ratio between the diameter of coarse-particle materials and the pore diameter of strata determines the distribution area, distribution shape, and development tendency of the initial formation zone. The relatively smaller light sands (0.3 mm or 0.5 mm) possess a good synergistic effect with slurry particles, allowing the formation of stable bridge structures. This filter-cake has a denser structure and better quality. However, adding relatively larger light sands (0.75 mm or 1.0 mm) results in a higher filtrate mass or a failure to form filter-cake. The effectiveness of the filter-cake formation is greatly improved as the additive content of the light sands increases. However, as the additive content reaches a certain value, the improvement effect clearly weakens. The coarse-particle materials have a certain scope of application, and therefore, to achieve the optimum performance, the diameters and content of the coarse-particle materials need to be reasonably determined depending on the pore characteristics of the strata. |
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| Keywords: | tunnel engineering filter-cake formation effectiveness model test slurry containing coarse-particle material slurry shield sandy strata |
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