重金属质量比对污染土土工性能的影响研究

在不同围压条件下, 对5种重金属含量不同的污染土试样进行了三轴试验、压缩试验和直剪试验。试验结果表明, 污染土的强度随着重金属元素含量增加显著降低, 围压增大对重金属含量低的污染土的强度的影响不显著, 质量比小于3%时, 峰值强度降低10%~15%, 质量比大于5%时, 峰值强度降低40%~50%。直剪试验结果表明 质量比小于3%的污染土抗剪强度-垂直压力曲线基本平行, 垂直压力与抗剪强度成正比, 抗剪强度降低幅度为5%~10%；质量比大于5%的污染土抗剪强度-垂直压力曲线表现为不规则, 抗剪强度降低45%～55%左右。压缩试验结果表明, 污染土与一般土的压缩量差别较大, 质量比超过5%以上时对压缩性的影响尤为显著。根据Mastsuoka-Nakai准则与三轴试验结果建立了污染土的本构关系, 经验证该模型在描述污染土的应力-应变关系方面更符合实际。

Effects of Mass Ratio of Heavy Metal on Geotechnical Properties of Contaminated Soil

The triaxial test, compression test and direct shear test were conducted on contaminated soil with different content of heavy metal under different surrounding pressure. Test results showed that strength of the contaminated soil was greatly reduced with an increased content of heavy metal, and it was little influenced by an increase in surrounding pressure if the content of heavy meal is lower. The peak strength decreased only by 10%~15% with mass ratio of heavy metal less than 3%, and decreased up to 40%~50% at mass ratio over 5%。The direct shear test showed that for the contaminated soil with mass ratio less than 3%, vertical stress was proportional to the shear strength which decreased by 5%~10%, while with mass ratio over 5%, the vertical stress was in no proportional to the shear strength which decreased by 45%~50%. The compression test indicated that the contaminated soil is quite different from the common soil with compression significantly influenced as mass ratio over 5%. A constitutive relation was established for the contaminated soil based on Mastsuoka-Nakai criterion and triaxial test results, with which the obtained strain-stress relationship for contaminated soil was better in accordance with the actual situation.