垃圾填埋场斑脱土衬里可行性评价

简文星; 嘉门雅史; 金山民政

垃圾填埋场斑脱土衬里可行性评价

1.
中国地质大学工程学院, 湖北武汉 430074
2.
京都大学工程学院环境工程系, 日本京都 606-8501
3.
大阪地质研究所, 日本大阪 550-0012

基金项目: 中日政府互换奖学金(1999年)项目

详细信息

作者简介:
简文星(1967-), 男, 副教授, 1998年获中国地质大学地质工程博士学位, 1999年在日本京都大学从事博士后研究工作, 研究方向为卫生垃圾填埋场的稳定性及人工复合粘土衬里的可行性.E-mail: wxjian@cug.edu.cn

中图分类号: X53;X705
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出版历程
- 收稿日期: 2003-05-18
- 刊出日期: 2003-09-25

Feasibility Evaluation of Landfill Bentonite-Enhanced Liners

1.
Faculty of Engineering, China University of Geosciences, Wuhan 430074, China
2.
Department of Global Environmental Engineering, Graduate School of Engineering, Kyoto University, Kyoto 606-8501, Japan
3.
Geo-Research Institute, Osaka 550-0012, Japan

摘要

摘要: 首先对斑脱土衬里(粘土-斑脱土、砂-斑脱土) 进行变水头实验, 得粘土-斑脱土的渗透系数为6.0×10^-9~3.0×10^-8cm/s, 砂-斑脱土的渗透系数为1.0×10^-9~3.0×10^-9cm/s.从防渗角度分析, 2种斑脱土混合物均适合作垃圾填埋场的底层衬里.然后对斑脱土衬里进行持水与水迁移实验, 评价斑脱土衬里水的迁移特性.以水迁移实验为基础, 模拟斑脱土衬里与地基5种不同含水量的条件, 对斑脱土衬里进行直接剪切实验, 测定斑脱土衬里的剪切强度及斑脱土衬里与地基接触面的剪切强度.再对斑脱土衬里进行三轴固结不排水实验, 测定其总剪切强度与有效剪切强度.实验结果表明: 地下水具有很大的潜力从地基流向斑脱土衬里, 从而大大提高斑脱土衬里的含水量; 随着含水量的增加, 粘土-斑脱土、砂-斑脱土衬里的抗剪强度逐渐减小.根据实验所获得的抗剪强度参数, 选择日本山谷型垃圾填埋场典型剖面, 对山谷型垃圾填埋场进行稳定性评价.结果表明: 对于角度小于20°的缓倾角山谷型垃圾填埋场, 使用粘土-斑脱土、砂-斑脱土作为底层衬里是稳定的.因此, 2种斑脱土混合物适合作山谷型垃圾填埋场的底层衬里.
- 斑脱土衬里 /
- 渗透实验 /
- 持水与水迁移实验 /
- 直剪实验 /
- 三轴固结不排水实验 /
- 垃圾填埋场的稳定性
Abstract: In the first part of this paper, the falling head permeability tests were conducted on bentonite-enhanced liner (BEL) specimens (sand-bentonite and clay-bentonite mixtures) to obtain the hydraulic conductivity. The results show that the hydraulic conductivity of clay-bentonite is about 6.0×10^-9—3.0×10^-8cm/s, and that of sand-bentonite about 1.0×10^-9—3.0×10^-9cm/s. Compared with the standard hydraulic conductivity used in Japan (1.0×10^-6 cm/s), the hydraulic conductivity of both clay-bentonite and sand-bentonite is much lower. Then, the water retentivity and water migration tests were performed on the two liner specimens to evaluate the water retention and migration properties from saturated/unsaturated base soil. Based on the above tests, direct shear tests were conducted to obtain the internal shear strength of BEL specimens and the interface shear strength between BEL and base soil under five different water control conditions. Triaxial shear tests were also conducted on the two liner specimens to obtain the total and effective shear strength. Test results show that pore water in the underlying base soil has great potential to migrate to the BELs, resulting in a significant increase in water content of BELs, and the shear strength of both BEL internal and BEL/base interface tends to decrease with the increase of water content in BELs. Finally, the slope stability of a typical canyon solid waste landfill related to the two liners under various conditions was analyzed with the obtained shear strength parameters. Landfills at a gentle slope (with the total angle of the slope not greater than 20 degree) do not fail in both cases of sand-bentonite liner and clay-bentonite liner. Therefore, sand-bentonite and clay-bentonite mixtures are suitable for landfill bottom liners.
- bentonite-enhanced liner /
- permeability test /
- water retentivity and water migration test /
- direct shear test /
- consolidated undrained triaxial compression test /
- landfill stability

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图 1 柔壁变水头实验仪示意图

Fig. 1. Apparatus of falling head permeability test

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图 2 渗透实验结果

Fig. 2. Results of falling head permeability test

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图 3 含水量与毛细作用力的关系

Fig. 3. Matric suction against water content for clay-bentonite, sand-bentonite and Toyoura sand

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图 4 砂-斑脱土水迁移实验结果

a.1, 2, 3, 4表示丰浦砂的初始含水量分别为8.4%, 17.1%, 24.6%及饱和时实验样品含水量的变化; b.1, 2, 3, 4表示丰浦砂的初始含量分别为9.8%, 14.3%, 18.6%及饱和时实验样品含水量的变化

Fig. 4. Water migration test results for sand-bentonite

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图 5 三轴固结不排水实验结果

Fig. 5. Results of consolidated undrained triaxial compression test

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图 6 山谷型垃圾填埋场综合地质剖面

Fig. 6. Cross section of a canyon solid waste landfill

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图 7 工况Ⅲ稳定系数与水平地震系数关系

1.沿粘土-斑脱土内部; 2.沿粘土-斑脱土与地基的接触面; 3.沿砂-斑脱土衬里的内部; 4.沿砂-斑脱土与地基接触面; 5.沿垃圾焚烧灰尘内部

Fig. 7. Variation of factor of safety with horizontal seismic coefficients for case Ⅲ

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表 1 实验材料物理特征

Table 1. Properties of materials

表 2 斑脱土衬里的基本物理特征

Table 2. Properties of bentonite mixture liners

表 3 直接剪切实验的状况与实验结果

Table 3. Conditions and results of direct shear tests

表 4 稳定性计算工况

Table 4. Assumed condition in stability analysis

参考文献(15)

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