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针对苏北黄泛区粉土路基受季节性冻融的影响,对水泥、石灰、粉煤灰不同组合的12种粉土路基改良填料开展冻融环境下抗压强度、质量损失(抗冲刷能力)的试验研究,分析不同组分下改良土的抗冻性能。结果表明,随着冻融循环次数的增加,粉质土抗压性能及质量完整性逐步衰减,衰减过程具有明显的阶段性。水泥粉煤灰改良土的抗冻效果明显优于水泥石灰组合,水泥石灰改良土在冻融循环后由于材料脆性变强而使得填料更易崩解。在各组分对冻融破损的抑制方面,水泥的胶结作用显著,在水泥质量分数为2%~7%时,可以抑制冻融导致的强度衰减,提升抗冲刷能力;石灰能一定程度改善填料抗冻性,但由于其自身的膨胀性又对质量损失控制、抗冲刷能力存在不利影响;而粉煤灰的添加却可以在抑制强度衰减尤其保持质量完整性方面发挥着重要的作用。添加5%水泥及15%粉煤灰的改良组合可使苏北黄泛区季节性冻融环境下粉土路基具有较优异的抗冻性能。
Aiming at the effect of seasonal freezing and thawing on the silty subgrade in the northern part of the North Jiangsu Province, 12 kinds of silt subgrade modified fillers with different combinations of cement, lime and fly ash were tested for their compressive strength and mass loss under freeze-thaw environment ) Of the experimental study, analysis of different components of the modified soil frost resistance. The results show that with the increase of the number of freeze-thaw cycles, the compressive properties and the mass integrity of silty soil gradually decay, and the decay process has obvious stages. The anti-freezing effect of the cement-fly ash modified soil is obviously better than that of the cement-lime combination. After the freeze-thaw cycle of the cement-lime modified soil, the filler is more easily disintegrated due to the material brittleness. In the inhibition of freeze-thaw damage of each component, the cementation effect of cement is remarkable. When the mass fraction of cement is 2% -7%, the strength attenuation caused by freezing and thawing can be suppressed and the anti-erosion ability can be improved; lime can improve the filler Frost resistance, but because of its own expansibility and quality control, anti-scour ability has an adverse effect; and fly ash addition can inhibit the intensity of attenuation, in particular, to maintain the integrity of the quality plays an important role. The improved combination of 5% cement and 15% fly ash can make the silt subgrade more excellent in frost resistance under the seasonal freezing and thawing circumstance in the northern part of the northern Jiangsu.