生物聚合物对高含水量淤泥压缩渗透特性的影响

Effect of biopolymers on compressibility and permeability of high water-content sludge

摘要:

生物聚合物可以有效改善土体的力学性质。为评估生物聚合物改性淤泥在实际工程中的应用前景,研究黄原胶（XG）、海藻酸钠（SA）、阳离子瓜尔胶（GG）对高含水量淤泥压缩性和渗透性的影响。通过一维渗透固结试验,探究生物聚合物种类及掺量对土体结构屈服应力、压缩指数、渗透系数等指标的影响。同时,通过电镜扫描（SEM）和压汞试验（MIP）,分析生物聚合物改性高含水量淤泥的微观机制。结果表明,生物聚合物改性淤泥中的黏土-聚合物网络结构使其压缩性降低。随着掺量的增加,改性淤泥结构屈服应力增大,压缩性减小。当竖向有效应力大于结构屈服应力时,改性淤泥C_c显著增大,且随着掺量的变大而提高。生物聚合物改性淤泥渗透性明显降低,所用聚合物中XG的效果最显著,在1.5%掺量时达到两个数量级。

Abstract:

Biopolymers can effectively improve the mechanical properties of soil. In order to evaluate the application prospect of biopolymer-modified sludge in practical engineering, the effects of xanthan gum (XG), sodium alginate (SA), and cationic guar gum (GG) on the compressibility and permeability of high water-content sludge were studied. On the basis of one-dimensional osmotic consolidation test, the effects of different types and dosages of biopolymers on the yield stress, compression index, and coefficient of permeability of soil were investigated. Meanwhile, the microscopic mechanism of the modification of high water-content sludge by biopolymer was analyzed by scanning electron microscopy (SEM) and mercury intrusion porosimetry (MIP) tests. Results show that the compressibility of modified sludge was reduced because of the formation of clay-polymer network structure. With increasing dosage, the compressibility of modified sludge decreased, while the structural yield stress increased gradually. When the vertical effective stress was greater than the structural yield stress, the C_c value of the modified sludge increased significantly, and it further increased with the increase in dosage. The permeability of the modified sludge was significantly reduced. Among the polymers used in the study, XG had the most significant effect, achieved two orders of magnitude when the dosage was 1.5%.