Statistical damage model for fiber-reinforced vegetation concrete substrate
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摘要: 为研究纤维加筋植被混凝土基材的本构模型和损伤演化规律,考虑围压和纤维掺量两个因素,基于Weibull分布建立了能反映基材力学特性的统计损伤模型,给出了模型参数的确定方法,探讨了Weibull分布参数与围压、纤维掺量的关系。利用该模型对基材三轴试验结果进行对比验证;根据基材的破坏准则,推导了损伤阈值的确定方法;通过分析损伤演化特征与微元体的失效过程,对基材应力–应变关系和损伤软化规律进行了阐释。分析结果表明该模型曲线与试验结果吻合度较高,能较好反映纤维加筋基材加载过程中的损伤软化特性;加筋基材损伤阈值与峰值应变之比保持在0.4~0.6之间。本文研究为准确分析和评价基材的力学性质提供了理论参考。Abstract: This study attempts to investigate the constitutive model and damage evolution law of the fiber-reinforced vegetation concrete substrate. Taking the two factors of confining pressure and fiber content into account, a statistical damage model that can reflect the mechanical properties of the substrate is established based on the Weibull distribution. The method for determining model parameters is given, and the relationship among the Weibull distribution parameters, the confining pressure and the fiber contents is discussed. The model is then used to verify the results of the triaxial tests on the substrate. According to the destruction criterion of the substrate, the method for determining the damage threshold is deduced. By analyzing the damage evolution characteristics and the failure process of the micro-element, the stress-strain relationship and the law of damage softening of the substrate are elaborated. The results show that the model curves agree well with the tests, which can reflect the damage softening characteristics during the loading process of the fiber-reinforced substrate. Besides, the ratio of the damage threshold to the peak strain is found to range from 0.4 to 0.6. This study provides a theoretical reference for the accurate analysis and evaluation of the mechanical properties of substrate.
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表 1 纤维加筋基材抗剪强度测试值
Table 1 Values of shear strength tests on fiber-reinforced substrate
λ/% 棕榈纤维加筋基材 玄武岩纤维加筋基材 c/kPa φ/(°) c/kPa φ/(°) 0 75.4 33.7 75.4 33.7 0.2 95.5 33.4 86.6 33.5 0.4 99.0 33.9 91.1 33.7 0.6 104.0 34.0 94.1 33.3 0.8 108.3 34.1 97.4 33.7 表 2 棕榈纤维加筋基材弹性模量实际值与拟合值
Table 2 Actual and fitted values of elastic modulus of palm fiber-reinforced substrate
λ/% σ3=10 kPa σ3=30 kPa σ3=50 kPa 试验值/MPa 拟合值/MPa 相对误差 试验值/MPa 拟合值/MPa 相对误差 试验值/MPa 拟合值/MPa 相对误差 0 7.98 7.78 -0.0251 10.16 10.55 0.0384 11.95 11.84 -0.0092 0.2 8.63 8.55 -0.0093 10.80 11.19 0.0361 12.62 12.41 -0.0166 0.4 9.66 9.32 -0.0352 11.66 11.83 0.0146 12.77 12.99 0.0172 0.6 11.30 10.10 -0.1062 12.36 12.46 0.0081 13.61 13.56 -0.0037 0.8 11.46 10.87 -0.0515 12.52 13.10 0.0463 13.61 14.14 0.0389 表 3 玄武岩纤维加筋基材弹性模量实际值与拟合值
Table 3 Actual and fitted values of elastic modulus of basalt fiber-reinforced substrate
λ/% σ3=10 kPa σ3=30 kPa σ3=50 kPa 试验值/MPa 拟合值/MPa 相对误差 试验值/MPa 拟合值/MPa 相对误差 试验值/MPa 拟合值/MPa 相对误差 0 7.98 7.87 -0.0132 10.16 10.86 0.0691 11.95 12.25 0.0249 0.2 8.60 8.83 0.0270 12.58 11.88 -0.0552 13.83 13.23 -0.0432 0.4 10.34 9.79 -0.0531 12.88 12.90 0.0020 14.76 14.21 -0.0371 0.6 10.71 10.75 0.0037 13.62 13.93 0.0225 15.21 15.19 -0.0007 0.8 11.74 11.71 -0.0023 14.67 14.95 0.0186 16.21 16.18 -0.0023 表 4 纤维加筋基材损伤阈值(σ3=30 kPa)
Table 4 Damage thresholds of fiber-reinforced substrate (σ3=30 kPa)
λ/% 棕榈纤维加筋基材 玄武岩纤维加筋基材 εd/% εd/εp εd/% εd/εp 0 2.81 0.58 2.73 0.55 0.2 3.16 0.51 2.76 0.57 0.4 3.12 0.45 2.88 0.56 0.6 3.08 0.49 2.51 0.43 0.8 3.04 0.49 2.43 0.47 注:λ=0(空白试样)Efc分别采用式(15),(16)计算。 -
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