椰丝纤维长度对土体抗剪强度和抗压强度的影响

Effect of coir fiber length on shear strength and compressive strength of soil

【目的】探究在客土喷播基材中添加不同长度纤维材料对土体抗剪强度和抗压强度的影响。【方法】采用控制变量的试验方法,以不同长度(1、2、3、4、5 cm)的椰丝纤维和砂土为试验材料,按0.4%(w/w)的质量比混合后进行了室内三轴试验和无侧限抗压试验。【结果】(1)各长度纤维加筋土在各围压下的主应力差峰值强度和抗压强度峰值都大于无纤维加筋的素土;(2)随着纤维长度的增加,主应力差峰值强度、内聚力、内摩擦角和加筋效果系数都呈现出先增加后减少的趋势,且在长度为3~4 cm时,强度达到峰值;(3)随着纤维长度的增加,抗压强度峰值,主应力差强度峰值及破坏后的残余强度都得到明显提升,应力-应变曲线逐渐由应变软化型过渡为应变硬化型。【结论】掺量为0.4%、长度为3~4 cm的椰丝纤维可以有效提升土体的抗剪强度和抗压强度。

【Objective】Fiber material is one of the main materials for soil spraying in slope vegetation restora-tion.The aim of the study is to investigate the The influence of the length of fiber material added to the soil spray-sown substrate on the shear strength and compressive strength of soil.【Method】This paper adopted the test method of control variables.The indoor triaxial test and unconfined compression test were carried out by mixing coconut fiber and sand soil of different lengths(1,2,3,4,5 cm)at the mass ratio of 0.4%(w/w).【Result】The results of the study showed that:(1)The peak strength of the principal stress difference and the peak compressive strength of each length treatment at each circumferential pressure were greater than those of the plain soil without fiber reinforcement,and both could effectively improve the residual strength of the soil body after shear and compression damage,indicat-ing that the addition of coir fibers could effectively improve the strength and toughness of the soil body.(2)With the increase of fiber length,the principal stress difference peak strength,cohesion,internal friction angle and reinforce-ment effect coefficient all showed a trend of increasing and then decreasing,and the strength reached the peak at the length of 3~4 cm.This fully indicated that there was an optimal length for the effect of fiber length on soil stability.(3)At the same time,the peak compressive strength,the peak principal stress difference strength and the residual strength after damage all increased significantly with increasing fiber length,and the stress-strain curve gradually changed from a strain-softening type to a strain-hardening type.【Conclusion】When the content of coir fiber is 0.4%and the length of coir fiber is 3~4 cm,the shear strength and compressive strength of soil can be effectively im-proved.