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摘要:
土石混合体边坡在我国分布范围广, 且其材料组成复杂, 受到了众多学者的关注。为了科学合理地评估土体参数的空间变异性对土石混合体边坡稳定性的影响, 基于随机场理论, 选取有效抗剪强度参数黏聚力
c 和内摩擦角φ 作为随机变量, 采用局部平均法模拟随机场, 在MATLAB中实现随机场参数生成, 在考虑土石混合体块石真实形状和块石含量基础上, 采用Python语言脚本方式, 将随机场参数映射到有限元软件中的土石混合体边坡, 应用强度折减法计算边坡稳定安全系数。计算结果显示, 土石混合体边坡的稳定安全系数符合正态分布, 随着土石混合体边坡块石含量增加, 边坡稳定安全系数的均值从1.005增长至1.095, 边坡也由浅层破坏逐渐发展为深层破坏。块石质量分数均为35%时, 块石粒径较大土石混合体边坡稳定性安全系数为1.334, 块石粒径较小土石混合体边坡稳定安全系数为1.064。相比于确定性计算结果, 考虑土体参数空间变异性的稳定安全系数更高。因此, 在进行土石混合体边坡稳定性分析时, 应充分考虑土体有效抗剪强度参数空间变异性, 避免出现设计过于保守的情况。Abstract:The extensive distribution and complex material composition of soil-rock mixture slopes in China have attracted significant attention from scholars.
Objective This study aims to scientifically and rationally assess the impact of the spatial variability of soil parameters on the stability of soil-rock mixture slopes.
Methods Based on the random field theory, the effective shear strength parameters cohesion
c and internal friction angleφ are selected as random variables. The local averaging method is used to simulate the random field, with random field parameter generation conducted in MATLAB. Python scripts are employed to map the random field parameters to the soil-rock mixture slope via finite element software, accounting for the actual shape and content of block rocks in the soil-rock mixture. The strength reduction method is then applied to calculate the slope stability safety factor.Results The results reveal that the stability safety factor of soil-rock mixture slopes follows a normal distribution. As the block stone content increases, the mean value of the stability safety factor rises from 1.005 to 1.095, reflecting a transition from shallow to deep failure. For block stone content of 35%, the stability safety factor reaches 1.334 for larger block stones and 1.064 for smaller ones. Compared to deterministic calculation results, incorporating the spatial variability of the soil parameters yields higher stability safety factor.
Conclusion Therefore, in soil-rock mixture slope stability analyses, the spatial variability of effective shear strength parameters must be fully considered to prevent overly conservative designs.
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表 1 二维随机场常用的相关函数
Table 1. Correlation functions for a 2D random field
函数名称 相关函数 指数函数 $\rho\left(\tau_1, \tau_2\right)=\exp \left(-2 \sqrt{\frac{\tau_1^2}{\delta_1^2}+\frac{\tau_2^2}{\delta_2^2}}\right)$ 高斯函数 $\rho\left(\tau_1, \tau_2\right)=\exp \left[-\pi\left(\frac{\tau_1^2}{\delta_1^2}+\frac{\tau_2^2}{\delta_2^2}\right)\right]$ 可分离的指数函数 $\rho\left(\tau_1, \tau_2\right)=\exp \left[-2\left(\frac{\left|\tau_1\right|}{\delta_1}+\frac{\left|\tau_2\right|}{\delta_2}\right)\right]$ 注:字母含义见正文 表 2 土石混合体边坡模型参数
Table 2. Parameters for the soil-rock mixture slope model
组成成分 密度/(kg·m-3) 弹性模量/MPa 泊松比v 黏聚力c/kPa 内摩擦角φ/(°) 本构模型 块石 2 700 15 000 0.25 — — 理想弹性模型 土体 2 000 50 0.30 12.38 20 摩尔-库伦破坏准则 表 3 有效抗剪强度参数的分布特征参数
Table 3. Distribution characteristic parameters of effective shear strength parameters
分布特征参数 黏聚力c/kPa 内摩擦角φ/(°) 均值μ 12.38 20.00 标准差σ 2.47 4.00 表 4 稳定安全系数
Table 4. Stability safety factor
块石质量分数/% 确定性计算结果 均值 标准差 最小值 最大值 0 0.997 1.005 0.033 0.917 1.138 5 0.997 1.008 0.058 0.910 1.127 15 1.005 1.012 0.082 0.917 1.137 25 1.061 1.079 0.062 0.915 1.151 35 1.064 1.095 0.033 1.000 1.153 #35 1.334 — — — — 注:块石质量分数0为均质土坡;块石质量分数#35%相较于其他情况,块石粒径增大;下同 -
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