聚醚胺-230处治膨胀土的膨胀-压缩-收缩试验

Experimental Study on Swelling-compression-shrinkage Behavior of Expansive Soil Treated with Polyetheramine

基于高效、快速、大面积处治膨胀土的工程需求,以聚醚胺-230作为水溶性膨胀土稳定剂并成功实现对膨胀土的快速处治。模拟常规路基施工中配制含水率后的压实填筑方法,讨论聚醚胺水溶液代替水按照掺入配比的方法处治膨胀土的效果与土壤特性变化。通过膨胀、固结与收缩试验比较了膨胀土与不同聚醚胺-膨胀土质量比对应处治土的膨胀、压缩与收缩特性。结果表明:聚醚胺的迅速吸附能抑制并调控膨胀土的膨胀与收缩劣害性,同时使压实处治土展现出土壤结构的强化特性。处治土的膨胀、压缩和收缩指标均显著降低;样品制备为干密度1.62 g·cm^(-3)时,膨胀土可被处治为低膨胀性、低收缩性、中压缩性的处治土。基于吸附机理,聚醚胺的掺入量主要影响着处治效果,但存在处治极限即无法完全抑制膨胀与收缩特性。主要处治机理通过对扫描电子显微镜图像与膨胀土中黏粒部分的X-衍射分析进行表征,干燥的提取黏粒中蒙皂石层间距1.49 nm变化为处治后的1.36 nm,可解释为聚醚胺的插层效应导致蒙皂石矿物层间的离子水化受到抑制。聚醚胺单层平铺吸附于蒙皂石矿物层间,层间钙离子无法水化至2层水分子以上扩大层间距。土壤颗粒表面水敏性显著降低,土壤微观结构图像直观地揭示了聚醚胺在膨胀土中的吸附导致的水化抑制与土壤结构强化效应。

To address the engineering need for an efficient,rapid,and large-scale approach for treatment of expansive soils,polyetheramine-230 was successfully utilized as a water-soluble stabilizer for expansive soils in this study.Common compaction and filling techniques with varying moisture levels typically employed in the traditional road construction were emulated.The aim was to assess the impact of substituting water with a polyetheramine solution,following specific mixing ratios,on the treatment of expansive soils and its influence on soil properties.Swelling,consolidation,and shrinkage tests were conducted to compare the treatment effects on expansive soils,and different mass ratios of polyetheramine-treated expansive soils were analyzed.The swift adsorption capacity of polyetheramine effectively mitigates the expansion and shrinkage tendencies of expansive soils,bolstering the structural characteristics of the compacted treated soil.When the specimen is prepared with a dry density of 1.62 g·cm^(-3),the expansive soil can be effectively treated to exhibit a low expansivity,minimal shrinkage,and moderate compressibility.The treatment efficacy is primarily influenced by the dosage of polyetheramine,guided by adsorption mechanisms.However,there exists a treatment threshold,beyond which the complete suppression of expansive and shrinkage characteristics becomes unachievable.The key treatment mechanism was elucidated through an X-ray diffraction analysis of the clay fraction within the expansive soil and scanning electron microscopy images.The initial interlayer spacing of native clay of 1.49 nm decreases to 1.36 nm.This phenomenon can be elucidated by the intercalation effect of polyetheramine,which hinders the ion hydration within the interlayers of montmorillonite minerals.The polyetheramine monolayer uniformly adsorbs onto the montmorillonite mineral layers,impeding the hydration of interlayer calcium ions beyond two layers of water molecules and thereby contracting the interlayer spacing.Furthermore,the water sensitivity of treated soil particles experiences a substantial decrease.The microstructural analysis further elucidates the inhibitory effects on the hydration and strengthening of the soil structure by the adsorption of polyetheramine in the expansive soil.