椰丝纤维加筋土的抗剪强度及界面数量特性研究

Study on Shear Strength and Interface Quantity Characteristics of Coir Fiber Reinforced Soil

客土喷播是边坡及矿山修复的一种重要方式。为了找到客土喷播基材中纤维材料的最优纤维长度及掺量,通过室内直接剪切试验研究了不同长度及掺量的椰丝纤维加筋土体的抗剪强度特性,并对土-纤维剪切界面的纤维数量特征进行了统计分析。结果表明:不同长度椰丝纤维加筋土体的抗剪强度随着法向应力的增加呈线性增加趋势,这符合摩尔-库伦定律的基本规律;纤维长度对土体抗剪强度及其参数(内聚力和内摩擦角)的影响显著大于纤维掺量的影响,在纤维长度为3 cm时,土体内聚力达到最大,在纤维长度为4 cm时,内摩擦角达到最大;最优长度对抗剪强度的影响在不同法向应力下表现出一定差异性,随着法向应力的增加,最优纤维长度也增加;纤维长度和掺量对界面纤维数量、数量差值及纤维分散系数都有显著的影响;椰丝纤维在剪切面上的根数与纤维掺量之间并非线性关系,而是呈现指数型上升的趋势;随着纤维长度的增加,界面纤维数量差值呈现先下降后上升的趋势,而纤维的分散系数整体呈现线性上升的趋势,这对纤维在土体中的分散带来一定的考验。总之,椰丝纤维作为一种可持续性的植物纤维材料,加筋土体时可增强土体的界面作用力,明显提升土体的抗剪强度,有利于边坡的稳定,具有广阔的应用前景。

Guest soil spraying is an important form of slope and mine restoration.In order to find out the optimal fiber length and content of the substrate suitable for guest soil spraying,The shear strength characteristics of coir fiber reinforced soil with different lengths and contents are investigated by indoor direct shear test,and the fiber quantity characteristics of the fibers at the soil-fiber shear interface are statistically analyzed.The result shows that(1)The shear strengths of coir fiber reinforced soil with different lengths increase linearly with the increase of normal stress,which conforms to the basic law of Mohr-Coulomb theory.(2)The influence of fiber length on shear strength and its parameters(cohesion and internal friction angle)are significantly greater than the influence of fiber content.When the fibers length is 3 cm,the cohesion in the soil reaches the maximum.When the fibers length is 4 cm,the internal friction angle reach the maximum.(3)The influence of the optimal length on the shear strength is different under different normal stresses.As the normal stress increases,the optimal fiber length also increases.(4)The fiber length and content have significant influence on the quantity of interface fiber,the quantity difference and the fiber dispersion coefficient.(5)The relationship between the quantity of coir fibers on the shear surface and the fiber content is not linear,but shows an exponential increase.(6)As the fiber length increases,the interfacial fiber quantity difference tends to decrease at first and then increase,while the overall fiber dispersion coefficient tends to increase linearly,which poses a certain challenge to the dispersion of fiber in soil.In short,as a sustainable plant fiber material,coir fiber can enhance the interface force of soil when reinforcing soil,significantly improve the shear strength of soil,and is conducive to slope stability.It has broad application prospects.