聚丙烯纤维加筋黄土的抗剪强度和崩解特性

为检验聚丙烯纤维加筋黄土对边坡坡面的防护效果，基于室内直剪试验和崩解试验，研究了纤维含量、纤维长度及含水率对加筋黄土抗剪强度和抗崩解特性的影响，获得了加筋黄土的最佳配比，并以此为基础开展了现场坡面防护试验。研究结果表明:相比于素黄土，聚丙烯纤维加筋黄土的黏聚力最高提升113.8%，内摩擦角最高提升23.3%，崩解速率最高降低87.5%，聚丙烯纤维可有效提高黄土的抗剪强度和抗崩解特性；随着纤维含量和纤维长度的增长，聚丙烯纤维加筋黄土的黏聚力分别呈现先增大后减小和先急剧增大后增幅趋缓的变化趋势，崩解速率分别呈现先减小后增加和持续减小的变化趋势；从抗剪强度方面考虑，聚丙烯纤维加筋黄土的最佳纤维含量为0.3%，最佳纤维长度为15 mm，从崩解特性方面考虑，聚丙烯纤维加筋黄土的最佳纤维含量为0.5%，最佳纤维长度为19 mm，相比较而言，两者崩解速率的相对变化明显小于其抗剪强度的相对变化，故确定聚丙烯纤维加筋黄土的最佳纤维含量为0.3%，最佳纤维长度为15 mm；随着含水率的增加，聚丙烯纤维加筋黄土的黏聚力、内摩擦角和崩解速率均呈现减小趋势，其变化关系符合三次多项式函数或Logistic函数关系；现场测得聚丙烯纤维加筋黄土防护坡面平均侵蚀深度约为3 mm，说明聚丙烯纤维加筋黄土的坡面防护效果明显。 

Shear strength and disintegration properties of polypropylene fiber-reinforced loess

To test the protective effect of polypropylene (PP) fiber-reinforced loess on slope surface, the influences of fiber content, fiber length and moisture content on the shear strength and disintegration properties of PP fiber-reinforced loess were evaluated. The optimal mixing ratio for the reinforced loess was obtained to conduct field slope surface protection tests. Research result shows that compared to unreinforced loess, the cohesion and internal friction angle of PP fiber-reinforced loess maximally increase by 113.8% and 23.3%, respectively, while the disintegration rate reduces by a maximum of 87.5%. Therefore, PP fiber can effectively improve the shear strength and disintegration resistance of loess. As the fiber's content and length increase, the cohesion of PP fiber-reinforced loess increases first and then decreases, and first increases sharply and then increases gradually, respectively. Meanwhile, the disintegration rate decreases first and then increases, and decreases continuously, respectively. For the shear strength, the optimal fiber content is 0.3%, and the optimum fiber length is 15 mm. For the disintegration properties, the optimal fiber content is 0.5%, and the optimum fiber length is 19 mm. In contrast, the relative difference in the disintegration rate between the two samples with different fiber contents and lengths is smaller than that in the shear strength. Hence, the optimal fiber content is 0.3%, while the optimum fiber length is 15 mm. Higher water content leads to lower cohesion, internal friction angle, and disintegration rate of PP fiber-reinforced loess, and the relationships between the water content and the three parameters conform to cubic polynomial or Logistic functions. Based on the field tests, the average erosion depth of the slope protected with PP fiber-reinforced loess is approximately 3 mm, indicating that the PP fiber-reinforced loess provides a significant slope surface protection. 3 tabs, 15 figs, 35 refs.