Study on dynamic modulus and damping ratio of sand gravel under different loading ratios
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摘要: 为探究加载比和围压对砂砾料动力特性的影响,通过大型动三轴试验,研究不同加载比和围压作用下砂砾料动模量和阻尼比的变化规律。研究结果表明:(1)随着加载比的增大,动应变显著增大,孔压明显上升,最大阻尼比增大;(2)试验数据更能反映出阻尼比随动剪应变发展的变化规律,综合考虑各动力参数的变化,建议砂砾料动模量和阻尼比试验加载比选择范围为1.5~2.0;(3)采用分段拟合法对动应变小于0.01%和大于0.01%的试验数据进行拟合,直线与试验点的拟合度均大于0.96,分段拟合不同试验条件下砂砾料本构关系更为合理;(4)不同试验条件下动剪切模量比与参考剪应变具有良好的归一性,通过二元线性回归得到砂砾料最大动剪切模量关于围压和加载比的经验公式。该方法可为砂砾料动三轴试验及数据处理提供参考。Abstract: In order to explore the dynamic characteristics of sand gravel under the action of loading ratio, through large-scale dynamic triaxial test, the change law of dynamic modulus and damping ratio of sand gravel under different loading ratios and confining pressures is studied, and the influence of different loading ratios and confining pressures on the dynamic parameters of sand gravel is analyzed. The results show that: (1) With the increase of loading ratio, the dynamic strain increases significantly, the pore pressure increases significantly, and the maximum damping ratio increases; (2) The test data can better reflect the variation law of damping ratio with the development of dynamic shear strain. Considering the changes of various dynamic parameters, it is suggested that the selection range of dynamic modulus and damping ratio test loading ratio of gravel is 1.5~2.0; (3) The test data with dynamic strain less than 0.01% and dynamic strain greater than 0.01% are fitted by the subsection fitting method. The fitting degree between the straight line and the test point is greater than 0.96, and the subsection fitting is more reasonable under different test conditions; (4) Under different test conditions, the dynamic shear modulus ratio and the reference shear strain have good normalization, and the test data are reliable. Through binary linear regression, the empirical formula of the maximum dynamic shear modulus of gravel about confining pressure and loading ratio is obtained. This method can provide a reference for dynamic triaxial test and data processing of gravel materials.
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Key words:
- sand gravel /
- dynamic modulus /
- damping ratio /
- loading ratio /
- maximum dynamic shear modulus
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表 1 不同加载比试验方案
Table 1. Test schemes with different loading ratios
试验材料 围压/kPa Kc 加载比 动应力幅值/kPa 砂砾料 400 1.5 1.0 60 120 180 240 300 360 420 480 540 1 000 150 300 450 600 750 900 1 050 1 200 1 350 1 600 240 480 720 960 1 200 1 440 1 680 1 920 2 160 400 1.5 32 47 71 107 160 240 360 540 / 1 000 79 119 178 267 400 600 900 1 350 / 1 600 126 190 284 427 640 960 1 440 2 160 / 400 2.0 17 34 68 135 270 540 / / / 1 000 42 84 169 338 675 1 350 / / / 1 600 68 135 270 540 1 080 2 160 / / / 400 2.5 6 14 35 86 216 540 / / / 1 000 14 35 86 216 540 1 350 / / / 1 600 22 55 138 346 864 2 160 / / / 表 2 不同加载比下双曲线模型参数
Table 2. Hyperbolic model parameters under different loading ratios
加载比 围压/kPa a/10−7 b/10−5 R2 εd<0.01% εd>0.01% εd<0.01% εd>0.01% εd<0.01% εd>0.01% 1.0 400 - 7.09 - 1.04 - 0.984 1 000 - 5.15 - 0.40 - 0.981 1 600 - 4.61 - 0.22 - 0.945 1.5 400 4.81 7.42 2.99 1.24 0.999 0.981 1 000 4.18 5.57 0.95 0.40 0.974 0.978 1 600 3.15 4.27 0.67 0.25 1.000 0.965 2.0 400 4.18 7.40 5.03 1.29 0.999 0.993 1 000 3.85 5.71 1.37 0.40 0.999 0.991 1 600 2.99 4.21 1.12 0.27 1.000 0.977 2.5 400 4.09 7.44 4.10 1.13 0.995 1.000 1 000 2.60 4.91 3.83 0.50 0.967 0.992 1 600 2.07 4.21 2.89 0.27 0.964 0.979 表 3 不同试验条件下最大动剪切模量Gdmax
Table 3. Maximum dynamic shear modulus Gdmax under different test conditions
加载比 围压/kPa Gdmax/MPa εd<0.01% εd>0.01% 1.0 400 - 530.54 1 000 - 730.23 1 600 - 816.25 1.5 400 782.05 506.19 1 000 899.42 675.15 1 600 1 193.24 880.24 2.0 400 908.76 507.79 1 000 976.04 658.73 1 600 1 256.68 892.82 2.5 400 920.09 505.12 1 000 1 448.05 765.08 1 600 1 812.21 892.78 表 4 不同加载比下模型参数
Table 4. Model parameters under different loading ratios
加载比 n k1 k2 1.0 0.316 30.33 3 263.47 1.5 0.387 90.22 2 723.05 2.0 0.390 141.43 2 699.59 2.5 0.417 240.70 2 665.72 -
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