PFC3D Particle Flow Simulation of Nano-Clay Modified Loess Triaxial Test
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摘要: 基于PFC3D软件研究不同纳米材料、掺量、围压、干密度对改良黄土力学性能的影响，确定改良黄土宏细观之间的参数关系，通过建立改良黄土数值模型、三轴试验，获得了改良黄土的应力–应变曲线。将数值模拟的结果与室内试验的结果相比较，通过数值模拟和室内三轴试验，得出的改良黄土抗剪强度指标基本吻合。试验结果表明：（1）围压一定时，改良黄土试样偏应力随纳米黏土掺量的增加而增大；改良黄土的应力与应变正相关，不同围压时，表现为软化型和强硬化型；（2）当凹凸棒土掺量小于2%时，数值模拟得到的抗剪强度总体小于室内试验得到的抗剪强度，材料大于2%时则相反；（3）纳米蒙脱土改良黄土数值试样材料掺量小于等于4%时，数值模拟得到的抗剪强度大于室内试验的抗剪强度，大于4%则相反。
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关键词:
- 凹凸棒土 /
- 纳米蒙脱土 /
- 改良黄土 /
- 三轴试验 /
- PFC3D颗粒流模拟试验
Abstract: PFC3D software was used to study the influence of different nanomaterials, dosage, confining pressure, and dry density on the mechanical properties of improved loess, and determine the parameter relationship between macro and meso of improved loess. Through a numerical model of improved loess and a three-axis experiment, the stress-strain curve of improved loess was obtained. The results of the numerical simulation were compared with the results of indoor experiments, and the shear strength index of improved loess was consistent. The experimental results showed that: (1) When the confining pressure is constant, the deviatoric stress of the improved loess sample increases with the increase of nano-clay content. The stress and strain of the improved loess are positively correlated. When the confining pressure is different, it shows a softening type and a strong hardening type. (2) When the content of attapulgite is less than 2%, the shear strength obtained by numerical simulation is generally lower than that derived from laboratory tests; conversely, when the content exceeds 2%, the situation is reversed. (3) When the content of nano-montmorillonite modified loess in numerical test samples is less than or equal to 4%, the shear strength obtained through numerical simulation is higher than that measured in laboratory tests; conversely, when the content exceeds 4%, the situation is reversed. -
表 1 凸棒土改良黄土抗剪强度指标
质量掺量/% 干密度/(g·cm−3) c/kPa φ/(°) c'/kPa φ'/(°) 0 1.35 18.47 11.95 14.23 28.55 1.45 24.80 13.00 17.41 33.78 1.55 31.39 14.36 23.03 35.38 1.65 44.98 17.94 33.06 39.05 1 1.35 29.74 13.06 16.41 36.58 1.45 37.58 15.37 23.30 38.83 1.55 44.78 18.36 34.69 40.02 1.65 68.65 21.41 45.92 44.99 2 1.35 27.62 12.53 16.10 35.66 1.45 34.70 15.25 21.06 37.44 1.55 38.86 17.30 31.53 38.46 1.65 59.55 20.06 43.64 43.12 4 1.35 24.46 12.30 15.66 35.24 1.45 32.48 15.01 20.43 37.24 1.55 36.94 16.28 27.36 37.27 1.65 53.01 18.88 39.77 42.94 6 1.35 22.79 12.12 15.12 34.26 1.45 29.74 14.42 18.24 37.16 1.55 35.57 15.56 25.80 36.83 1.65 49.84 18.56 37.41 41.39 
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表 2 纳米蒙脱土掺量改良黄土抗剪强度指标
质量掺量/% 干密度/(g·cm−3) c/kPa φ/(°) c'/kPa φ'/(°) 0 1.35 18.47 11.15 14.23 28.55 1.45 27.80 13.00 17.41 33.78 1.55 35.39 14.36 23.03 35.38 1.65 44.98 17.34 33.06 38.05 1 1.35 29.12 12.30 17.55 32.96 1.45 35.15 13.86 21.90 36.09 1.55 41.45 15.36 33.86 37.88 1.65 51.02 18.06 45.31 40.39 2 1.35 33.56 12.65 24.11 35.10 1.45 44.75 14.77 32.83 37.44 1.55 49.43 17.42 43.75 38.61 1.65 59.15 20.18 56.76 42.69 4 1.35 30.31 12.49 22.04 33.85 1.45 40.05 15.47 27.94 36.37 1.55 44.43 15.43 35.23 38.17 1.65 55.67 19.03 47.67 41.92 6 1.35 29.89 12.30 20.58 32.75 1.45 37.18 13.76 24.51 35.94 1.55 42.24 14.95 32.69 37.45 1.65 53.72 18.54 44.71 40.42
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表 3 基本计算参数
参数 颗粒切向
刚度/(N·m−1)颗粒法向
刚度/(N·m−1)粘结强度
/kPa土颗粒密度
/(kg·m−3)颗粒最小
半径/(×10−3m）颗粒最大
半径/(×10−3m)摩擦系数
f上下墙刚度
/(N·m−1)圆柱墙刚度
/(N·m−1)孔隙率 素黄土 1×105 1×105 31.39 2710 0.6 1.7 0.26 1×107 1×105 0.55 凹凸棒土 2.4×104 2.4×104 38.86 2740 0.2 0.35 0.31 0.93，0.95
0.96，0.98纳米蒙脱土 1.4×104 1.4×104 49.43 2740 0.15 0.55 0.32 0.93，0.95
0.96，0.98
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表 4 凹凸棒土改良黄土抗剪强度指标
凹凸棒土掺量（质量）/% c/kPa φ/(°) c'/kPa φ'/(°) 1 32.16 13.25 21.44 30.57 2 33.45 15.13 24.59 34.22 4 35.74 17.85 28.18 36.19 6 39.62 18.59 30.72 40.52
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表 5 纳米蒙脱土改良黄土抗剪强度指标
纳米蒙脱土掺量（质量）/% c/kPa φ/(°) c'/kPa φ'/(°) 1 32.33 11.86 18.29 30.17 2 36.42 13.05 24.48 32.53 4 38.10 15.27 28.06 35.61 6 42.18 19.25 34.96 38.75
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