Correlations between physical and mechanical property indexes of Shanghai soil based on support vector machine
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摘要:
针对上海地区土体物理力学指标开展相关性分析,结合多个工程场地获取的土体室内试验数据,采用支持向量机算法构建了土体塑性指数、液性指数与压缩系数的相关性分析模型,并结合误差指标对模型参数进行优化。将支持向量机模型与传统的线性、多项式拟合方法结果对比分析,表明该模型预测结果与实际结果较为吻合,且该模型另一优势在于能够从更多的数据中进行更深度的挖掘来提升自身的鲁棒性。考虑到不同土体的工程性质差异较大,进一步研究该模型的预测性能与适用性,就每个测试样本点预测偏差与其物理指标建立二者的关系曲线,结果表明可塑性小的中压缩性土体相较于高压缩性土体的预测偏差更小,模型更加稳定与准确,可为上海地区土体压缩性相关研究提供参考。
Abstract:Correlation analysis of physical and mechanical indexes of Shanghai soil was carried out. Using the support vector machine algorithm, the authors constructed a correlation analysis model of soil plasticity index, liquidity index and compressibility coefficient based on the soil indoor test data obtained from several engineering sites. Then the model parameters were optimized by combining the error indexes. Comparing the results of support vector machine model with those of traditional linear and polynomial fitting methods, it was shown that the prediction results of the model are basically consistent with the actual results, and another advantage of model is that it can carry out deeper mining from more data to improve its robustness. Considering the engineering properties of different category soils are quite different, the authors further analyzed the performance and applicability of model, and established the relationship curve between the forecast bias of each testing sample and its physical indexes. The results indicate that the error of medium compressible soil is smaller than high compressible soil, and the model is more stable and accurate, which could provide a reference for the research of soil compressibility in Shanghai.
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表 1 土的物理力学指标统计
Table 1. Statistics of physical and mechanical indexes of soil
土体类型 统计量 物理力学指标 参数值 最小值 最大值 平均值 标准差 变异系数 淤泥质粘土 221 压缩系数a1-2/MPa−1 0.66 1.60 0.84 0.27 0.32 含水量w/% 24.40 63.40 42.93 6.54 0.15 塑限WP/% 17.00 31.30 22.80 2.92 0.13 液限WL/% 26.50 53.90 37.42 6.10 0.16 塑性指数IP 9.40 22.80 14.62 3.38 0.23 液性指数IL 0.52 2.57 1.41 0.32 0.23 湿密度ρ/(cm·s−3) 1.62 1.97 1.76 0.06 0.03 土粒比重Gs 2.71 2.75 2.73 0.01 0.0039 粘土 31 压缩系数a1-2/ MPa−1 0.21 0.98 0.57 0.22 0.39 含水量w/% 24.00 52.60 36.22 7.66 0.21 塑限WP/% 16.50 27.50 22.17 2.55 0.12 液限WL/% 30.50 48.10 37.64 4.57 0.12 塑性指数IP 10.80 20.60 15.47 2.41 0.16 液性指数IL 0.35 1.93 0.92 0.43 0.47 湿密度ρ/(cm·s−3) 1.70 2.02 1.87 0.10 0.05 土粒比重Gs 2.72 2.75 2.73 0.01 0.0037 粉质粘土 198 压缩系数a1-2/ MPa−1 0.07 1.28 0.41 0.21 0.51 含水量w/% 18.20 52.00 30.97 6.27 0.20 塑限WP/% 15.00 31.00 21.46 2.40 0.11 液限WL/% 25.40 53.80 35.15 4.63 0.13 塑性指数IP 9.00 22.80 13.68 2.61 0.19 液性指数IL -0.31 1.84 0.72 0.41 0.57 湿密度ρ/(cm·s−3) 1.67 2.10 1.90 0.09 0.05 土粒比重Gs 2.71 2.75 2.73 0.01 0.0037 砂质粉土 137 压缩系数a1-2/ MPa−1 0.10 0.83 0.39 0.18 0.46 含水量w/% 19.90 46.40 31.51 5.01 0.16 塑限WP/% 13.00 25.70 20.14 2.44 0.12 液限WL/% 22.40 43.40 30.29 3.45 0.11 塑性指数IP 7.10 17.70 10.15 1.91 0.19 液性指数IL 0.35 1.90 1.10 0.33 0.30 湿密度ρ/(cm·s−3) 1.73 2.03 1.84 0.07 0.04 土粒比重Gs 2.69 2.74 2.71 0.01 0.0025 表 2 不同输入变量预测结果误差对比
Table 2. Error comparison of forecast results for different input variables
输入变量 误差指数 R2 MAE RMSE MSE 塑性指数、液性指数 0.860 0.116 0.144 0.021 塑性指数 0.525 0.212 0.265 0.070 液性指数 0.228 0.269 0.338 0.114 表 3 不同核函数预测结果误差对比
Table 3. Error comparison of forecast results for different kernel functions
核函数 误差指数 R2 MAE RMSE MSE RBF 0.886 0.100 0.130 0.017 多项式 0.876 0.109 0.136 0.018 线性 0.86 0.116 0.144 0.021 表 4 不同误差项惩罚系数预测结果误差对比
Table 4. Error comparison of forecast results of penalty coefficients of different error item
误差项惩罚系数C 误差指数 R2 MAE RMSE MSE 5 0.903 0.094 0.120 0.014 1 0.886 0.100 0.130 0.017 0.5 0.873 0.105 0.137 0.019 表 5 不同方法的压缩系数预测结果误差对比
Table 5. Error comparison of prediction results of compression coefficients by different methods
算法 误差指数 R2 MAE RMSE MSE SVR算法 0.911 0.08 0.115 0.013 线性拟合 0.859 0.118 0.144 0.021 多项式拟合 0.892 0.101 0.127 0.016 表 6 不同物理指标预测结果误差对比
Table 6. Error comparison of prediction results for different physical indexes
指标 变化范围 误差指标 MAE RMSE MSE 塑限WP 16—20 0.071 0.080 0.006 20—26 0.082 0.111 0.012 26—32 0.129 0.023 0.151 液限WL 25—35 0.067 0.080 0.006 35—45 0.104 0.141 0.020 45—55 0.122 0.144 0.021 塑性指数IP 7.5—12.5 0.064 0.079 0.006 12.5—17.5 0.081 0.108 0.012 17.5—22.5 0.130 0.158 0.025 液性指数IL 0.2—0.7 0.069 0.087 0.008 0.7—1.2 0.107 0.133 0.018 1.2—1.8 0.094 0.122 0.015 表 7 中高压缩性土预测结果误差对比
Table 7. Error comparison of prediction results of medium and high compressible soil
土体类型 误差指数 MAE RMSE MSE 中压缩性土 0.069 0.085 0.007 高压缩性土 0.120 0.150 0.023 -
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