纤维纱加筋黄土一维蠕变特性试验研究

Experimental study on one dimensional creep behavior of loess reinforced with fiber yarn

将纺织废旧布料经过开松、分梳、切断制成纤维纱,在黄土中掺入一定比例及长度的纤维纱,制备成纤维纱加筋黄土,利用一维蠕变仪研究在不同竖向荷载作用下,纤维纱加筋黄土的一维蠕变变形特性。试验结果表明:在不同竖向荷载作用下,纤维纱加筋黄土的蠕变应变均小于素黄土的蠕变应变,纤维纱加筋对于抑制黄土的蠕变变形具有积极作用;当竖向荷载大于400k Pa时,纤维纱加筋黄土达到稳定蠕变的时间相较于素黄土更长;随着纤维纱掺加比例及纤维纱掺加长度的增大,纤维纱加筋黄土的蠕变应变呈现出先减小后增大的变化趋势;纤维纱最佳掺加比例为0.3%,纤维纱最佳掺加长度为30 mm。构建可以反映土体进入蠕变阶段后,长期强度稳定性能的蠕变指数表达式,当竖向荷载在400~800 kPa时,蠕变指数增长显著,当竖向荷载大于800 kPa时,蠕变指数随竖向荷载的增大逐渐趋于稳定。结合一维蠕变试验数据,建立了考虑纤维纱掺加比例及纤维纱掺加长度影响的纤维纱加筋黄土一维蠕变经验模型。

The Loess reinforced with fiber yarn was prepared by adding a certain proportion and length of fiber yarn,originating from waste textile fabric through opening,combing and cutting,into loess,and one dimensional creep deformation characteristics of fiber reinforced loess under different vertical loads were studied by using one-dimensional creep apparatus.The test results show that,under different vertical loads,the creep strain of the fiber reinforced loess is smaller than that of the plain loess,indicating that fiber yarn reinforcement has a positive effect on restraining the creep deformation of loess.When the vertical load is greater than 400 kPa,the time for the fiber reinforced loess to reach stable creep is longer than that of the plain loess.With increasing the proportion and the length of fiber yarn,the creep strain of the loess reinforced by fiber yarn first decreases and then increases.The optimum blending ratio and the optimum blending length of fiber yarn are 0.3%and 30 mm respectively.The creep index expression was constructed to reflect the long-term strength stability of soil after entering the creep stage.When the vertical load is between 400 and 800 kPa,the creep index increases significantly.When the vertical load is greater than 800 kPa,the creep index tends to be stable.Based on the data of one-dimensional creep test,an empirical model of one-dimensional creep of loess reinforced with fiber yarn is established considering the influence of fiber yarn proportion and fiber yarn length.