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冰川冻土 ›› 2021, Vol. 43 ›› Issue (5): 1489-1497.doi: 10.7522/j.issn.1000-0240.2021.0100

• 寒区工程与灾害 • 上一篇    下一篇

人工冻结法协同竖井淋洗原位修复污染黏性土的可行性试验

陈雄志1,2(),毋文涛2,张军2,芮大虎2,3(),李国玉3,伊藤譲4   

  1. 1.江西地质局 第三地质大队,江西 九江 332000
    2.河南理工大学 土木工程学院,河南 焦作 454000
    3.中国科学院 西北生态环境 资源研究院 冻土工程国家重点实验室,甘肃 兰州 730000
    4.摄南大学 土木工学科,日本 大阪 572-8508
  • 收稿日期:2021-03-10 修回日期:2021-07-05 出版日期:2021-10-31 发布日期:2021-12-09
  • 通讯作者: 芮大虎 E-mail:619105343@qq.com;dhrui@ hpu.edu.cn
  • 作者简介:陈雄志,高级工程师,主要主要从事岩土工程及地质灾害研究工作. E-mail: 619105343@qq.com
  • 基金资助:
    国家自然科学基金项目(41771070);冻土工程国家重点实验室开放基金项目(SKLFSE201917)

Feasibility of remediating polluted clayey soil in situ by artificial freezing and PVD-enhanced system

Xiongzhi CHEN1,2(),Wentao WU2,Jun ZHANG2,Dahu RUI2,3(),Guoyu LI3,Yuzuru ITO4   

  1. 1.The Third Geological Brigade of Jiangxi Geological Bureau,Jiujiang 332000,Jiangxi,China
    2.School of Civil Engineering,Henan Polytechnic University,Jiaozuo 454000,Henan,China
    3.State Key Laboratory of Frozen Soil Engineering,Northwest Institute of Eco-Environment and Resources,Chinese Academy of Sciences,Lanzhou 730000,China
    4.Department of Civil Engineering,Setsunan University,Osaka 572-8508,Japan
  • Received:2021-03-10 Revised:2021-07-05 Online:2021-10-31 Published:2021-12-09
  • Contact: Dahu RUI E-mail:619105343@qq.com;dhrui@ hpu.edu.cn

摘要:

针对黏性土淋洗效率低下问题,提出了人工冻结法协同竖井淋洗原位修复污染土壤的方法。通过垂直布设冻结板,水平冻结土体的竖井淋洗模型试验,研究冻结过程中土中温度场、水分场分布及融解期的排水方式,探讨了人工冻结法协同竖井淋洗原位修复污染黏性土的可行性。研究表明:利用人工冻结法,使未冻土侧水分或淋洗液在“冻吸力”作用下向冻结锋面迁移,然后利用塑料排水板完成融化水(淋出液)与土壤分离的方案可行,能够解决抽液过程中抽液井和注液井之间土体容易形成渗流通道出现优先流,导致淋洗效率低下的问题。在分步冻结模式下,未冻土侧水分在“冻吸力”作用下向冻土侧迁移,冻结-吸水量为22.78 L,融化-排水量为24.60 L;经历一次冻融循环后,相同冻结模式下冻结-吸水量达到30.40 L,在负压抽吸模式下排水量达到44.21 L。该研究结果为今后原位修复污染黏性土提供了新的思路。

关键词: 人工冻结法, 竖井淋洗, 冻结板, 负压抽吸

Abstract:

In view of the low washing efficiency of clayey soil, the method of artificial freezing and prefabricated vertical drains (PVD) enhanced soil flushing was put forward to remediate polluted soil in situ. In this study, the temperature field and moisture field distribution in the soil during the freezing process and drainage way during the thawing period were studied via the shaft leaching model test of vertically setting freezing plate with horizontally freezing soil. Furthermore, the feasibility of artificial freezing method cooperating with PVD-enhanced system for remediation of polluted clayey soil was discussed. The results show that it is feasible to use the artificial freezing method to transfer the water or eluent on the unfrozen side to the frozen front under the action of “freezing suction”, and then use the plastic drainage plate to separate the melting water (leachate) from the soil. On the basis of this method, the problem of the soil between the pumping well and the injection well is easy to form seepage channel and preferential flow, which results in the water or eluent can not fully contact with the pollutants adsorbed on the soil particles and the washing efficiency is low can be solved. the stepwise freezing mode, the moisture on the unfrozen side migrates to the frozen front under the action of “freezing suction”, the water absorption is 22.78 L, while the thawing-discharge volume is 24.60 L. After a freeze-thaw cycle, the water absorption in the freezing period under the same freezing mode reached 30.40 L, and the water discharge was 44.21 L, in the negative pressure suction mode. This technology provides a new idea for in-situ remediation of polluted clayey soil in the future.

Key words: artificial freezing method, PVD-enhanced system, freezing plate, negative pressure suction mode

中图分类号: 

  • P642.14