Experimental Study on Small Strain Shear Modulus of Fine Grained Soil in the Yellow River Alluvial Plain
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摘要: 本文通过采用原位波速法、弯曲元试验法和共振柱试验法,深入探讨了室内测试与原位波速法在小应变剪切模量试验中的差异。选取山东省境内黄河冲积平原典型场地细粒土钻孔资料,统计原位波速法和室内测试2种测试手段测得的剪切波速,并对测试结果进行对比分析。研究结果表明,在保持土的有效应力状态和减少土样扰动的基础上,原位波速法、弯曲元试验法和共振柱试验法测得的小应变剪切模量总体趋势一致,原位波速法的结果普遍小于室内测试的结果,但相对误差大多不超过10%。其中弯曲元试验法测试细粒土得到的小应变剪切模量与原位波速法的结果更为接近。建议工程实践中采用弯曲元试验法快速测得细粒土小应变剪切模量。将Rampello的经验公式描述的小应变剪切模量与实测结果进行对比,给出相关土层经验参数。研究结果可为该地区地下工程计算分析中小应变剪切模量的估算提供参考。Abstract: This study investigates the differences in small strain shear modulus (Gmax) measured using laboratory tests and the in-situ wave velocity method. The research utilizes data from a typical fine-grained soil site in the Yellow River alluvial plain, Shandong Province, China. The shear wave velocities measured by both in-situ wave velocity and laboratory methods (including bending element and resonant column tests) were compared. The results demonstrate a consistent trend in Gmax values across all methods, assuming the effective stress state of the soil is maintained and sample disturbance is minimized. While Gmax values from the in-situ wave velocity method tend to be lower than those from laboratory tests, the relative errors are generally less than 10%. The bending element test yields Gmax values that are closer to those obtained from the in-situ wave velocity method. It is suggested that, for engineering applications, the bending element test offers a quick and accurate means of determining the small strain shear modulus of fine-grained soils. Additionally, Rampello's empirical formula for Gmax is compared to the measured results, and the relevant empirical parameters for different soil layers are provided. These findings offer valuable insights for estimating the shear modulus at small and medium strains in underground engineering design and analysis in this region.
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表 1 试样参数
Table 1. Specimen parameters
取土地点 土样编号 取样深度/m 天然含水率/% 天然重度/(g·cm−3) 固结压力/kPa 土类 颜色状态 陵城区 K23-1 2.8 24.3 2.0 50 粉土 褐黄色,中密 K23-2 3.8 37.3 1.9 50 粉质黏土 黄褐色,可塑 K23-3 8.8 30.4 2.0 100 粉质黏土 黄褐色,可塑 K23-4 16.0 35.1 2.0 160 淤泥质土 黑灰色,可塑~软塑 K23-6 30.8 24.5 2.1 300 粉质黏土 褐黄色,可塑 K23-7 36.8 22.9 2.1 370 粉土 褐黄色,中密 K23-9 44.8 27.9 2.0 450 粉质黏土 褐黄色,可塑 K23-10 49.8 20.0 2.1 500 粉砂 褐黄色,密实 K23-14 60.8 22.5 2.1 600 黏质粉土 褐黄色,可塑~硬塑 K23-16 64.8 20.4 2.1 650 粉质黏土 黄褐色,硬塑 K23-17 67.8 19.5 1.9 680 粉砂 褐黄色,密实 庆云县 K19-2 7.8 21.7 2.0 100 粉质黏土 黄褐色,可塑 K19-3 13.8 24.3 2.1 140 粉质黏土 褐黄色,可塑 K19-4 16.8 20.8 2.1 170 粉质黏土 褐黄色,可塑 K19-5 21.0 22.0 2.1 200 黏土 黄褐色,可塑~硬塑 K19-7 32.0 27.7 2.0 300 粉质黏土 褐色,可塑~硬塑 K19-8 35.8 20.1 2.1 350 粉土 黄色,中密 K19-9 42.8 27.3 2.0 450 粉质黏土 褐黄色,可塑~硬塑 K19-11 48.8 25.1 2.0 500 粉质黏土 黄褐色,硬塑 K19-12 55.8 37.5 2.0 550 黏土 褐色,硬塑 注:原位波速法钻孔为取样钻孔。 表 2 3种方法剪切波速测试结果对比
Table 2. Comparison of shear wave velocity test results from three methods
取土点 测试深度/m 土层性质 现场测试结果/
(m·s−1)弯曲元测试结果/
(m·s−1)共振柱测试结果/
(m·s−1)相对误差/% 现场与弯曲元 现场与共振柱 弯曲元与共振柱 陵城区 2.8 粉土 164.0 170.9 201.9 4.2 23.1 18.1 3.8 粉质黏土 164.0 161.1 169.17 1.7 3.2 5.0 8.8 粉质黏土 179.0 191.0 231.2 6.7 29.2 21.1 16.0 淤泥质土 229.0 234.0 254.6 2.2 11.2 8.8 30.8 黏质粉土 307.0 310.0 282.8 1.0 7.9 8.8 36.8 粉土 337.0 355.0 323.0 5.3 4.2 9.0 44.8 粉质黏土 355.0 360.0 345.9 1.4 2.6 3.9 49.8 粉砂 348.0 335.0 324.7 3.7 6.7 3.1 60.8 黏质粉土 377.0 402.0 412.0 6.6 9.3 2.5 64.8 粉质黏土 434.0 431.0 453.0 0.7 4.4 5.1 67.8 粉砂 408.0 425.3 446.9 4.2 9.5 5.1 庆云县 7.8 黏质粉土 168.0 187.5 207.3 11.6 23.4 10.6 13.8 粉质黏土 182.0 238.7 242.4 31.2 33.2 1.6 16.8 粉质黏土 211.0 230.8 250.6 9.4 18.8 8.6 21.0 黏土 231.0 214.8 243.7 −7.0 5.5 13.4 32.0 粉质黏土 298.0 276.3 315.0 −7.3 5.7 14.0 35.8 粉土 311.0 281.9 277.8 −9.4 −10.7 −1.4 42.8 粉质黏土 335.0 347.7 344.6 3.8 2.9 −0.9 48.8 粉质黏土 357.0 342.3 365.2 −4.1 2.3 6.7 55.8 黏土 365.0 370.8 395.1 1.6 8.3 6.6 表 3 3种测试手段得到的土体小应变剪切模量Gmax值
Table 3. The small strain shear modulus of soil mass obtained with three testing methods
取样点 测试深度/m 土层性质 弯曲元Gmax/MPa 共振柱Gmax/MPa 现场测试Gmax/MPa 陵城区 3.8 粉质黏土 51.4 49.6 54.7 8.8 粉质黏土 64.7 73.7 108.0 16.0 淤泥质土 102.8 107.3 127.0 30.8 黏质粉土 198.9 202.8 168.7 36.8 粉土 240.8 267.2 221.2 44.8 粉质黏土 254.6 261.8 241.7 49.8 粉砂 253.1 234.6 220.4 60.8 黏质粉土 298.5 339.4 356.5 64.8 粉质黏土 391.8 386.4 426.8 67.8 粉砂 322.9 350.9 387.5 7.8 黏质粉土 56.2 70.0 85.5 庆云县 13.8 粉质黏土 69.9 120.2 124.0 16.8 粉质黏土 94.8 113.4 133.7 21.0 黏土 113.7 98.3 126.5 32.0 粉质黏土 173.2 148.9 193.5 35.8 粉土 200.2 164.5 159.7 42.8 粉质黏土 226.7 244.2 239.9 48.8 粉质黏土 256.2 235.4 268.1 55.8 黏土 261.1 269.4 306.0 表 4 土体经验参数S、n取值
Table 4. Values of soil empirical parameters S and n
数据类别 试验方法 e f(e) S n 参考文献 经验值 三轴试验、共振柱试验 0.5~6.2 $ {\left(1+e\right)}^{-2.4} $ 15000 ~50000 0.5 Vardanega等(2013) 本次测试 单孔波速测试 0.7~1.13 $ {\left(1+e\right)}^{-2.4} $ 30000 ~45000 0.5 本文结果 -
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