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摘要: 为预估路基的永久变形, 在万能材料试验机上对砂土进行了重复加载动三轴试验, 得到了砂土永久变形的发展曲线, 建立了塑性应变和荷载作用次数之间的关系式, 使用最小二乘法拟合出该式中的系数与含水量和回弹模量之间的回归公式, 并对回归公式进行了可靠性分析。当荷载作用次数为10000次时, 现有路基土永久变形模型预估结果与试验结果相对误差最小为52%, 最大高达376%;而系数与含水量和回弹模量之间的回归公式相关系数最小值为0.31, 平均值为0.41, 大于临界值0.28, 试验曲线与理论曲线相关系数大于0.99。分析结果表明: 建立的砂土永久变形预估公式可靠性较高, 而现有预估模型不适用于砂土。Abstract: In order to predict the permanent deformation of subgrade, a dynamic triaxial test of sandy soil under repeated load was made by using universal testing machine(UTM), the development curves of the deformation were got, the relationship formula between plastic strain and load acting time was found, the regression formulas among the coefficients of the relationship formula, water content and resilient modulus were fitted by using least square method, and their reliability was analyzed. Analysis result shows that when load acting time reaches 10 000, the minimum and maximum relative errors between permanent deformation prediction result and measured result are 52% and 376% respectively; the minimum and average correlative coefficients of the regression formulas are 0.31 and 0.41 respectively, which are greater than the critical value of 0.28, and the correlative coefficient between theoretical curve and measured one is more than 0.99. So the reliability of the proposed prediction formulas of permanent deformation for sandy soil is higher, but existing prediction model is not suitable for sandy soil.
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Key words:
- subgrade engineering /
- sandy soil /
- permanent deformation /
- repeated load test /
- prediction model
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表 1 土的基本性质
Table 1. Basic properties of soil
指标 最大干密度DMD/(g·cm-3) 最佳含水量/% 相对密度 液限/% 塑限/% 塑性指数 测定值 2.00 11.1 2.658 20.64 16.09 10.55 
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表 2 永久变形曲线拟合结果
Table 2. Fitting result of permanent deformation curve
工况 回弹应变εr 回弹模量/MPa R2 lg(ε0/εr) lg(ρ) lg(β) 91-105-48 0.001 25 38.40 0.998 7 0.702 430 536 5.439 378 -0.882 56 91-105-69 0.001 85 37.30 0.999 6 0.664 794 386 4.583 399 -0.769 70 91-110-48 0.001 55 30.97 0.998 0 0.690 481 894 4.612 529 -0.816 25 91-110-69 0.001 75 39.43 0.998 5 0.902 779 666 5.240 023 -0.851 34 91-120-48 0.001 60 30.00 0.998 7 0.426 307 892 3.258 652 -0.642 92 91-120-69 0.001 95 35.38 0.999 5 0.561 834 989 3.236 714 -0.635 37 96-105-28 0.000 60 46.67 0.999 5 0.758 407 192 6.594 742 -0.807 80 96-105-48 0.001 05 45.71 0.999 7 0.492 028 301 4.116 664 -0.722 60 96-105-69 0.001 40 49.29 0.998 9 0.566 521 666 3.750 246 -0.719 47 96-110-28 0.000 65 43.08 0.999 8 0.629 566 412 2.521 400 -0.509 38 96-110-48 0.001 20 40.00 0.999 7 0.573 065 095 2.815 113 -0.600 05 96-110-69 0.001 85 37.30 0.999 5 0.540 363 300 3.387 230 -0.684 79 96-120-28 0.001 00 28.00 0.998 6 0.597 695 186 2.760 121 -0.619 28 96-120-48 0.001 75 27.43 0.998 4 0.520 389 945 2.690 905 -0.593 07 96-120-69 0.002 15 32.09 0.999 3 0.508 921 011 3.037 904 -0.643 40
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