聚丙烯酸钠混合剂固化黄土特性研究

STUDY ON PROPERTIES OF LOESS SOLIDIFIED BY POLYACRYLATE SODIUM

黄土堆积松散、湿陷性强且极易被侵蚀的特性导致滑坡、泥石流、水土流失等地质灾害在黄土高原频发。为了缓解当今黄土地区土壤侵蚀,减少地质灾害的发生,本文利用聚丙烯酸钠混合剂对甘肃董志塬重塑黄土进行固化改良。通过室内崩解试验、渗透试验、水流冲蚀试验和三轴压缩试验等手段分析了不同配比下固化黄土的特性差异。结果显示,在经聚丙烯酸钠混合剂固化后,土体抗剪切破坏和水稳性能随着配比的提高而增大。当土体经聚丙烯酸钠混合剂浓度为3.5%的试剂固化后,固化效果趋于最佳,相比未加固土抗崩解和抗冲蚀性能均大幅提高,7次干湿循环后崩解率仅为1.15%,土体剪切破坏时的主应力差在100kPa、200kPa、300kPa围压下分别提高25.29%、28.23%、22.48%,渗透系数降低217.41倍。结合三轴试验数据、粒径级配和场发射扫描电镜从微观结构进行现象和机理解释,聚丙烯酸钠混合剂可将土粒包裹黏接,使土体中细小颗粒团聚在一起,从而改变土体粒径级配,促使土体黏聚力及内摩擦角增大,增强土体抗剪切性能,提高土体水稳性。聚丙烯酸钠混合剂对黄土的固化改良效果良好,将为缓解黄土高原地区土壤侵蚀,防灾减灾提供新方法。

Loess deposits are loose,collapsible,and easy eroded,which resulting in frequent geohazards such as landslides mudslides and water-soil loss in the Loess Plateau.To alleviate soil erosion and reduce the occurrence rate of geological disasters at present,this article uses sodium polyacrylate as the soil stabilizer to improve Dong Zhiyuan's remodeled loess in Gansu Province.Laboratory disintegration test,penetrant test,water erosion test,and triaxial compression test are adopted to analyze the property differences of solidified loess with different proportions.The results show that after solidification with the sodium polyacrylate mixture,the shear failure resistance and water stability performance of the soil are improved with the increase of the mixture proportion.Specially,with 3.5%of sodium polyacrylate mixture,the disintegration and erosion resistance is greatly improved.The disintegration rate is only 1.15%after seven dry and wet cycles.Compared with unreinforced soil,the principal stress difference at shear failure increases 25.29%,28.23%and 22.48%under 100kPa,200kPa and 300kPa,respectively.The penetration rate is reduced by 217.41 times.We explain the phenomenon and mechanism from the microstructure of the loess combined with the triaxial test date,size grading and field emission scanning electron microscope.The sodium polyacrylate mixture wraps and connects soil particles,which changes soil grain composition and grading,increases the cohesive force and internal friction angle between soil particles,and improves the soil shear resistance and water stability.The sodium polyacrylate mixture has a good solidification improvement effect on the loess.Our research results provide a new method for alleviating soil erosion and reducing disasters in the Loess Plateau.