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麻统孝, 庄恒, 王水, 倪浩, 潘月, 冯亚松, 刘登峰, 杜延军. 小型TRD工艺在有机污染场地垂直阻隔工程的应用研究[J]. 岩土工程学报. DOI: 10.11779/CJGE20240302
引用本文: 麻统孝, 庄恒, 王水, 倪浩, 潘月, 冯亚松, 刘登峰, 杜延军. 小型TRD工艺在有机污染场地垂直阻隔工程的应用研究[J]. 岩土工程学报. DOI: 10.11779/CJGE20240302
Field trial of constructing vertical barriers using small-scale TRD method at an organic compounds-contaminated site[J]. Chinese Journal of Geotechnical Engineering. DOI: 10.11779/CJGE20240302
Citation: Field trial of constructing vertical barriers using small-scale TRD method at an organic compounds-contaminated site[J]. Chinese Journal of Geotechnical Engineering. DOI: 10.11779/CJGE20240302

小型TRD工艺在有机污染场地垂直阻隔工程的应用研究

Field trial of constructing vertical barriers using small-scale TRD method at an organic compounds-contaminated site

  • 摘要: 相比于传统的非开挖施工装备,垂直切割搅拌器(小型TRD)具有占地面积小、施工均匀性好等优点,在污染场地垂直阻隔工程有广阔应用前景。本次研究以某有机污染场地垂直阻隔工程为依托,研究小型TRD工艺在垂直阻隔屏障施工的应用可行性。采用小型TRD工艺对原位土-六偏磷酸钠改良膨润土材料(SHMP-SB)施工,建造了长度分别为35.0 m和28.0 m,深度分别为7.0 m和5.0 m的垂直阻隔屏障。采用原位垂直切割搅拌工艺对原位土-活性炭改良膨润土材料(AC-SB)和原位土-有机黏土改良膨润土材料(OC-SB)施工,建造长度为7.0 m,深度为5.0 m的垂直阻隔屏障。通过现场试验与室内试验结合的方法,研究了膨润土材料的施工和易性,明确了水固比为4:1时,六偏磷酸改良膨润土材料可以满足小型TRD工艺对膨润土泥浆施工和易性的要求。垂直阻隔屏障施工14天后沿屏障深度方向取样,在室内开展颗分、含水率、液塑限、pH、特征元素(Na)全量分析和柔性壁渗透等实验,研究垂直阻隔屏障材料的土工参数沿深度方向的均匀性。结果表明,在清洁自来水渗透下,小型TRD工艺段屏障材料的渗透系数(1.3×10-10~2.4×10-10 m/s)低于原位垂直切割搅拌工艺段屏障材料的渗透系数(7.5×10-10~9.3×10-10m/s)。对比分析了小型TRD工艺段、原位垂直切割搅拌工艺段两类屏障材料的含水率、液限、特征元素(Na)全量、pH沿屏障深度方向的变异系数。结果表明,小型TRD工艺段屏障材料上述4个参数的变异系数低,沿深度方向的均质性更好。

     

    Abstract: This study presented field trial evaluation of using a novel vertical cutting equipment, namely small-scale TRD, to construct containment vertical barriers at an organic compounds-contaminated site. The small-scale TRD had merits of easy-construction at sites with relatively narrow space and superior uniformity of in-situ mixing as well. Vertical barrier with conventional method, namely, cutting-backfilling-mixing method, was also constructed for comparison purpose. The lengths and depths of barrier were 35.0 m and 7.0 m and 28.0 m and 5.0 m for the small-scale TRD, whereas those were 7.0 m and 5.0 m for the conventional method. The primary functional materials in the vertical barrier consisted of sodium hexametaphosphate-amended soil bentonite (SHMP-SB) for the small-scale TRD method, and organoclay-amended soil-bentonite (OC-SB) and activated carbon-amended soil-bentonite (AC-SB) for the conventional construction method. The workability of bentonite slurry used to construct the barrier via the small-scale TRD method was evaluated by Marshall viscosity, specific gravity, and slurry fluidity. The results showed that fluidity of sodium hexametaphosphate-amended bentonite slurry, prepared with a liquid-solid ratio of 4:1, could meet the construction requirement. 14 days post construction, the barriers were sampled and the coring samples were subjected to a series of particle size distribution, water content, liquid limit, pH, characteristic element (sodium) content, and flexible-wall hydraulic conductivity tests. The test results were used to assess the uniformity of geotechnical parameters along the barrier depths. Hydraulic conductivity test results revealed that the vertical barrier constructed by the small-scale TRD method exhibited lower hydraulic conductivity (1.3×10-10-2.4×10-10m/s) as compared to at constructed by the conventional construction method (7.5×10-10-9.3×10-10 m/s), indicating that SHMP-SB possessed superior impermeability. The barrier material constructed with small-scale TRD method had superior uniformity in terms of lower coefficient of variation values of moisture content, liquid limit, sodium content and pH along the depths.

     

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