纤维长度与掺量对加筋水泥土直剪特性的影响研究

Effects of Fiber Length and Content on Direct Shear Characteristics of Reinforced Cement-soil

为研究纤维掺量和纤维长度对水泥土力学性能的影响,选取珠海淤泥为试验对象,以聚丙烯纤维和水泥为加固材料,制作试样进行直剪试验。结果研究表明,聚丙烯纤维的加入可使水泥土的破坏形式由脆性破坏转变为塑性破坏;当纤维长度为9mm时,纤维掺量为0.4%,0.8%的水泥土平均抗剪强度较素水泥土分别提高了1.293,1.509倍,且纤维掺量越大,水泥土达峰值剪切应力所需的剪切位移越大;相同纤维掺量下,随着纤维长度的增加,水泥土抗剪强度呈先增大后减小的趋势,说明存在最优纤维长度使水泥土加固效果最佳;水泥土剪切位移随着纤维掺量的增加而增大,随着纤维长度的增加先增大后减小;水泥土黏聚力和内摩擦角均随着纤维掺量的增加而增大。

In order to study the influence of fiber content and fiber length on the mechanical properties of cement-soil, Zhuhai sludge was selected as the test object, and polypropylene fiber and cement were used as reinforcement materials to make samples for direct shear test. The research results show that the addition of polypropylene fiber can change the failure mode of cement-soil from brittle failure to plastic failure. Under the same fiber length(9 mm), the average shear strength of cement-soil with fiber content of 0.4% and 0.8% is 1.293 times and 1.509 times higher than that of plain cement-soil, respectively. The larger the fiber content is, the larger the shear displacement required for cement-soil to reach the peak shear stress is. Under the same fiber content, with the increase of fiber length, the shearing strength of cement-soil increases first and then decreases, indicating that there is an optimal fiber length to achieve the best reinforcement effect of cement-soil. The shear expansion of cement-soil increases with the increase of fiber content, and increases first and then decreases with the increase of fiber length. The cohesion and friction angle of cement-soil increased with the addition of fiber.