工程科学与技术2025，Vol.57Issue(6)：131-141,11.DOI:10.12454/j.jsuese.202301074
椰壳纤维加筋石灰改良土力学性能试验研究
Experimental Study on Mechanical Properties of Coconut Fiber Reinforced Lime Improved Soil Mechanics
摘要
Abstract
Objective The application of lime soil in engineering is further enhanced through the introduction of new materials for improvement and optimi-zation.Coconut fiber,a natural high-molecular material with superior mechanical properties,presents a promising solution.Utilizing coconut fi-ber to improve lime soil not only reduces construction costs but also increases soil strength and stability while mitigating resource waste and envi-ronmental pollution.Therefore,this study aims to enhance the mechanical properties of lime soil by employing coconut fiber as a reinforcing ma-terial and to examine its macroscopic mechanical behavior and microstructural characteristics. Methods The study analyzed the effects of different curing ages(7,14,28,and 60 days),coconut fiber content(0,0.25%,0.50%,0.75%,and 1.00%),dry and wet cycles(0,1,2,3,4,5,and 6 times),and compaction degrees(90%,93%,96%,and 99%)on the mechanical properties of lime soil by conducting the unconfined compressive strength test,dry and wet cycle test,nuclear magnetic resonance(NMR)test,and scanning electron microscope(SEM)test.These tests were performed to reveal the internal mechanism behind the improvement of the mechanical behav-ior of coconut fiber reinforced lime soil. Results and Discussions 1)For soils of the same age,the addition of coconut fiber significantly increased soil strength compared to soils without coconut fiber.As the amount of coconut fiber increased,the strength of the soil showed a tendency to first increase and then decrease,while the destructive strain of the soil gradually increased,changing the soil behavior from brittle to plastic.This occurred because the random distribution of coconut fiber formed a spatial mesh structure that restrained soil deformation and particle movement,improving soil integrity.However,fiber doping exceeding 0.75%created weak planes,reducing strength.Under different maintenance ages,the compressive strength gradually increased,and the destructive strain became smaller,showing brittle damage.This was mainly due to ion exchange,volcanic ash reaction,and carbonation reaction of lime,generating cementitious substances that reinforced the soil.2)Under the action of dry and wet cycles,the soil surface produced cracks and shedding,and its quality was obviously reduced.However,the mass loss of lime soil mixed with coconut fiber was significantly less,proving that coconut fiber inhibited crack formation and reduced surface detachment.When the compaction degree was the same,with the in-crease in the number of cycles,the soil mass showed a trend of increasing and then decreasing,reaching the maximum after the first cycle.This initial increase was attributed to the ongoing reactions of unreacted lime requiring moisture and the volcanic ash reaction during drying,generat-ing gelling substances that filled pores and increased strength.However,with further cycles,the lime was consumed,cementitious material and quality gradually reduced,leading to a decrease in compressive strength.When the cycle times were the same,an increased compaction degree led to greater soil compressive strength.A higher compaction degree resulted in smaller soil pores and a larger contact area between coconut fiber and soil,producing greater interface friction and higher soil strength.This indicated that the addition of coconut fiber and increased compaction degree enabled the soil to effectively resist the effects of wet and dry cycles.3)The microscopic test showed that the pore space of the soil exhib-ited a tendency to decrease and then increase with the number of wet and dry cycles,reaching the maximum and having the least cementitious ma-terial in the sixth cycle.The addition of fiber caused the pore space in the lime soil to increase significantly.Fiber guided the distribution of hy-drate,producing more gelling material that bonded the fiber and soil together.The rough fiber surface generated greater friction with the soil,lim-iting soil deformation. Conclusions Coconut fiber-lime-treated soil shows strong potential for application in road and slope engineering projects.The research findings provide valuable insights for practical implementation.The study demonstrates that incorporating coconut fiber effectively enhances the mechani-cal properties and durability of lime-treated soil,increases its strength,alters its failure mode from brittle to more plastic behavior,and improves its resistance to damaging wet-dry cycles.关键词
椰壳纤维/石灰/无侧限抗压强度/干湿循环/微观分析Key words
coconut fiber/lime/unconfined compressive strength/dry and wet cycle/microanalysis分类
土木建筑引用本文复制引用
李丽华,刘文,李玉涛,王翠英,叶治..椰壳纤维加筋石灰改良土力学性能试验研究[J].工程科学与技术,2025,57(6):131-141,11.基金项目
国家自然科学基金项目(52278347 （）
42407265) （）
湖北省基金创新群体项目(2024AFA009) （2024AFA009）
湖北省高等学校优秀中青年科技创新团队项目(T2023006) （T2023006）
