棕榈树在我国南方广泛种植,剥皮所得棕榈纤维具有一定的抗拉强度和较好的耐久性,近年来利用棕榈纤维加筋黏土在岩土工程中逐渐得到应用。为了研究棕榈纤维加筋黏土单轴应力状态下的力学性能、破坏形式及本构关系,选取长度分别为6、12、18 mm的棕榈纤维,按照纤维含量分别为0.2%、0.4%、0.6%、0.8%掺入黏土中,开展棕榈纤维加筋黏土的无侧限抗压强度试验。结果表明:黏土中掺加棕榈纤维后强度增加明显,在12 mm的筋材长度和0.8%的纤维含量组合下加筋效果最优,与素土相比,加筋后强度提高27%;加筋后的黏土破坏韧性好,残余强度高,并且破坏的过程比较缓慢,其原因为纤维在土体中形成了三维土网结构,限制了土颗粒的滑移,增强土体整体性,从而使得土体具有较好的延性;引入混凝土单轴受压应力-应变模型,分析棕榈纤维加筋黏土的无侧限抗压强度试验,将试验数据与模型曲线进行拟合,发现模型结果与试验结果具有良好的一致性。研究成果对棕榈纤维加筋土在岩土工程中的应用具有重要借鉴作用。
Abstract
Palm trees are extensively cultivated in southern China, and the palm fibers extracted from the tree bark boast notable tensile strength and durability. Consequently, palm fibers have gradually found application in geotechnical engineering in recent years to reinforce clay. To investigate its mechanical properties, damage patterns, and underlying constitutive relationships under stress, fibers measuring 6 mm, 12 mm, and 18 mm in length were chosen and incorporated into clay at mass ratios of 0.2%, 0.4%, 0.6%, and 0.8%,respectively.Unconfined compressive strength tests on the palm fiber-reinforced clay revealed a significant increase in clay strength following the addition of palm fibers.Optimal reinforcement was achieved by mixing 12 mm palm fibers into the clay at a 0.8% ratio, resulting in a 27% increase in strength compared to regular clay. Furthermore, the reinforced clay demonstrated exceptional damage tolerance and residual strength, prolonging the damage process. This was attributed to the formation of a three-dimensional soil network within the clay, which restricted soil particle slippage and enhanced clay integrity, ultimately leading to improved ductility. Furthermore, the uniaxial compressive stress-strain model for concrete was introduced to analyze the unconfined compressive strength test data. The results revealed a high degree of consistency between model results and test data. These research outcomes offer valuable insights for the utilization of palm fiber-reinforced clay in geotechnical engineering.
关键词
纤维加筋土 /
棕榈纤维 /
无侧限抗压强度 /
加筋机理 /
本构模型
Key words
fiber-reinforced soil /
palm fiber /
unconfined compressive strength /
reinforcement mechanism /
constitutive model
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基金
国家自然科学基金面上项目(51978249)
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