不同制样方法对木质素改良黄土力学特性影响

Effect of different sample preparation methods on mechanical properties of lignin improved loess

利用加水湿拌和泥浆搅拌2种方法对木质素改良黄土试样先进行均匀混合,后利用静压法在50mm×100mm圆柱形模具中两端压实制备试样,基于三轴仪对不同制样方法下改良土试样进行无侧限抗压强度试验和固结不排水三轴试验。试验结果表明:泥浆制样法获得改良土试样无侧限抗压强度值和固结不排水剪切强度值均高于加水湿拌法获得改良土试样强度值。结合扫描电镜试验对不同制样方法下改良土试样细观结构进行分析,发现对于木质素改良土,泥浆搅拌法获得的试样中木质素与黄土颗粒形成了新的胶结物和团聚物;而加水湿拌法获得试样中,木质素在土颗粒中仅起到加筋作用,未出现新的胶结物。该结果从微结构角度揭示了2种制样法制备试样的本质差异。

The lignin improved loess samples were uniformly mixed by water-wet mixing and mud fluid agitation,and then the samples were compacted in a 50 mm×100 mm cylindrical mold by static pressure at both ends.The unconfined compressive strength test and consolidation undrained triaxial test were carried out on the improved loess samples under different sample preparation methods based on the triaxial apparatus.The results showed that the unconfined compressive strength and the consolidated undrained shear strength of the improved soil samples obtained by the mud fluid agitation method are larger than the improved soil samples obtained by the water-wet mixing method.The microstructure of the improved loess samples with different sample preparation methods was analyzed by scanning electron microscope(SEM).It was found that the lignin and loess particles in the improved loess sample obtained by the mud fluid agitation formed new cementation and aggregate.However,in the sample obtained by the water-wet mixing,the lignin only acts as a reinforcement in the soil particles,and no new cementation appeared.The results revealed the essential difference between the two sample preparation methods from the perspective of microstructure.