Influence on the strength of soil-rock mixture made by the rock block orientation features based on numerical experiment
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摘要: 为了探讨土-石混合体的力学强度受块石定向性特征的影响，开发了二维椭圆块石集合体随机模型(2D Elliptic Block Collection Stochastic Model，简称EBCS2D)，并在此基础上进行了双轴压缩数值模拟。模拟结果显示土-石混合体的强度受块石定向性特征的影响，该影响规律与含石量显著关联。通过对各向异性屈服面曲线方程和数值模拟结果的拟合分析，验证了该屈服面曲线方程在表达土-石混合体强度方面的适应性。通过引入土-石相互作用单元的概念，阐明了在低、中、高3种含石量下，块石孤立作用和团簇作用交替主导，造成了块石定向性特征对土-石混合体力学强度的不同规律的影响。Abstract: This paper is to explore the influence on the strength of soil-rock mixture made by the rock block orientation features based on numerical experiment.The 2-D Elliptic Block Collection Stochastic Model (EBCS2D) was developed and a series of bia-axial compression numerical tests were conducted.The result indicates that the strength of soil-rock mixture is affected by the rock block orientation features.This effect is highly related to the block proportion.The results of numerical experiments are fitting in an anisotropic yield surface equation, which proves the equation is suitable on the soil-rock mixture, describing the impact of the block proportion and orientation.The soil-rock interactive unit is introduced to explain the mechanism and result.The soil-rock mixture strength changing patterns to the block orientation features are dominated by isolated effect or clustered effect.The dominating effects vary with the block proportion.
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Key words:
- soil-rock mixture /
- stochastic modeling /
- orientation feature /
- block proportion /
- soil-rock interaction
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图 1 EBCS2D方法模型建立过程示意图
a.圆形颗粒填充；b.圆形颗粒筛选；c.椭圆形颗粒生成；d.混合模型生成
Figure 1. Diagram of modeling procedure of EBCS2D method
图 4 典型模型网格剖分
含石量40.18%: a.无定向性；d.优势倾角45°
含石量29.06%: b.无定向性；e.优势倾角45°
含石量23.17%: c.无定向性；f.优势倾角45°Figure 4. Mesh in typical models
图 5 含石量40.18%试样的应力-应变图
Ⅰ、Ⅱ、Ⅲ为轴向应变的3个阶段
Figure 5. Stress-strain curve of 40.18% block proportion
图 6 含石量40.18%无定向性特征试样加载过程最大剪应变率云图
Figure 6. Nephogram of maximum shear strain rate in the soil-rock mixture of 40.18% block proportion with no preferred orientation
图 7 含石量40.18%有定向性特征θ0=75°试样加载过程最大剪应变率云图
Figure 7. Nephogram of maximum shear strain rate in the soil-rock mixture of 40.18% block proportion with preferred orientation θ0=75°
图 8 不同含石量不同定向性特征下的抗压强度
Figure 8. Compressive strength of the soil-rock mixtures with different block proportion and orientation
图 9 不同含石量定向性特征对试样抗压强度的影响
Figure 9. Impact on the compressive strength of the soil-rock mixtures with different block proportion and orientation
表 1 土-石混合体结构参数组合
Table 1. Parameters of soil-rock mixture structure
块石定向性特征 块石形状特征 含石量ABP/% θ0/(°) α2 P0 σ2 无定向性 1.5 0.01 40.1829.0623.17 — — 有定向性 0, 15, 30, 45, 60, 75, 90 0 
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表 2 土-石混合体中块石和土体力学参数
Table 2. Parameters of soil-rock mixture block and soil
名称 密度/(kg·m-3) 弹性模量E/MPa 泊松比μ 黏聚力c/kPa 内摩擦角φ/(°) 块石 2 580 1 040 0.2 500 38 土体 1 820 10 0.3 43 24
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表 3 拟合参数结果
Table 3. The results of fitting parameters
含石量φB/% μ λ α 决定系数 40.18 0.786 62 0.997 74 0.245 24 0.999 88 标准差 0.042 21 0.066 38 0.000 89 29.06 0.641 80 0.769 78 0.236 39 0.999 97 标准差 0.014 01 0.013 23 0.000 69 23.17 0.065 14 0.081 56 0.232 17 1.000 00 标准差 0.138 54 0.146 25 0.000 53
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