棕榈纤维加筋土抗剪强度特性及机理研究

Study on the Shear Strength Characteristics and Reinforcement Mechanism of Palm Fiber Reinforced Soil

为改善客土喷播后边坡浅层土体强度较低的问题,对棕榈纤维加筋土开展不固结不排水(Unconsolidated Undrained, UU)三轴试验,研究棕榈纤维加筋土在纤维掺量为0.35%、0.55%、0.75%、0.95%,纤维长度为5 mm、10 mm、20 mm、30 mm下不同加筋条件组合对土体抗剪强度特性的影响及其加筋机理.试验结果表明:在粉质黏土中掺入棕榈纤维可以显著提高土体的强度和抗变形能力.极限主应力差在纤维掺量为0.75%、纤维长度为20 mm时达到峰值,较素土提高172.9%;纤维掺量和长度等因素对黏聚力提升显著,较素土提升149.6%.对内摩擦角影响较小,在3°以内变化;对棕榈纤维进行SEM扫描电镜下观察后发现,棕榈纤维表面的沟槽可以增大纤维与土颗粒间的界面摩擦力和咬合作用,从而可以改善土体抗剪强度指标.

In order to address the problem of low shear strength of shallow slope soils,unconsolidated undrained(UU)triaxial tests were carried out on natural palm fiber reinforced soils to study the effect of different combinations of reinforcement conditions on the strength characteristics of soil and its reinforcement mechanism.Different fiber admixtures of 0.35%,0.55%,0.75%,0.95%and fiber lengths of 5 mm,10 mm,20 mm and 30 mm were investigated.The test results showed that mixing palm fiber into powdered clay soil can significantly improve the strength and deformation resistance of the soil.The ultimate principal stress difference reaches maximum for the fiber admixture of 0.75%and the fiber length of 20 mm,with the value increased by 172.9%compared with the plain soil.The internal friction angle is less influenced,with difference within 3°.,From the SEM scanning electron microscopy observation of the palm fibers,it is found that the grooves on the surface of palm fibers can increase the interfacial friction and interlocking effect betweenfibers and soilparticles,thereby improving the shear strength indicators ofthe soil.