RESEARCH ON INFLUENCING FACTORS OF EXPANSIVE DEFORMATION OF EXPANSIVE SOIL IN ANKANG AREA BASED ON PCA
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摘要: 为探究膨胀土物理力学性质指标对其膨胀变形影响。结合陕西安康地区某膨胀土工程实例,基于大量野外岩土勘察和室内测试数据资料,采用主成分分析法研究了膨胀土的膨胀变形与其物理力学性质指标间相关性及不同指标重要程度,建立了以主要物理力学指标为参数的膨胀土膨胀变形判别公式。影响膨胀土膨胀变形的物理力学指标可划分为反映外界环境的指标(含水率、饱和度、液性指数及含水比)、反映土体构造特征的指标(密度、干密度及孔隙比)、反映土体结构强度特征的指标(压缩系数和内摩擦角)及反映土体组成特征的指标(塑性指数和黏聚力);含水率是影响膨胀土膨胀变形的关键指标,所建立判别公式可为类似地区膨胀土膨胀变形的判别提供参考。Abstract: This paper aims to explore the influence of physical and mechanical properties of expansive soil on swelling deformation. Based on principal component analysis(PCA),the paper studied the correlation between the swelling deformation of expansive soil and its physical and mechanical properties,and established the discrimination formula of swelling deformation with main physical indexes as parameters. It completed the above work through a large number of field geotechnical investigation and indoor test of an expansive soil project in Ankang,Shaanxi Province. The results show that the physical and mechanical indexes affecting the swelling deformation of expansive soil can be divided into the four types of factors. The first type of factors reflects the environment including water content,saturation,liquid index and water content ratio. The second type reflects soil structure characteristics including density,dry density and void ratio. The third reflects structural strength characteristics of soil mass including compressibility and internal friction angle. The fourth reflects soil composition including plasticity index and cohesion. Moisture content is the key index affecting the expansion deformation of expansive soil. The prediction model can provide a reference for the judgment of expansive deformation of expansive soil.
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表 1 膨胀土物理力学指标统计值
Table 1. Test data of physical and mechanical indexes of expansive soil
数据类型 物理性质指标 力学性质指标 含水率ω /% 密度ρ /g·cm-3 干密度ρd /g·cm-3 孔隙比e 饱和度Sr /% 塑性指数Ip 液性指数IL 含水比ωb 压缩系数av/MPa-1 黏聚力c /kPa 内摩擦角φ/(°) 平均值 19.44 1.88 1.58 0.71 74.08 11.67 0.23 0.67 0.28 41.66 23.51 最大值 23.20 2.01 1.69 0.83 95.00 12.50 0.60 0.84 0.43 49.60 26.60 最小值 15.30 1.80 1.48 0.61 57.00 10.60 0.01 0.52 0.16 35.8 20.40 方差值 3.73 0 0 0 71.55 0.26 0.02 0.01 0 8.61 1.44 极差值 7.90 0.21 0.21 0.22 38.00 1.90 0.59 0.32 0.27 13.80 6.20 标准差 1.93 0.06 0.04 0.05 8.43 0.50 0.14 0.07 0.07 2.92 1.20 表 2 KMO和Bartlett检验结果
Table 2. KMO and Bartlett test result
Kaiser-Meyer-Olkin(KMO) 0.654 Bartlett 近似卡方 3386.733 df 55 Sig. 0 表 4 主成分荷载矩阵数值
Table 4. The value of the principal component load matrix
指标 成分 1 2 3 4 饱和度/% 0.981 -0.103 0.043 0.097 密度/g·cm-3 0.830 -0.554 -0.024 -0.012 含水率/% 0.829 0.488 0.099 0.189 含水比 0.810 0.562 0.023 -0.073 液性指数 0.716 0.515 0.194 -0.093 孔隙比 -0.408 0.897 0.089 0.125 干密度/g·cm-3 0.410 -0.893 -0.092 -0.138 内摩擦角/(°) -0.019 -0.132 0.709 -0.479 压缩系数/MPa-1 -0.332 -0.124 0.577 -0.116 黏聚力/kPa 0.075 -0.171 0.550 0.364 塑性指数 -0.105 -0.316 0.227 0.792 表 3 主成分特征值及贡献率
Table 3. Characteristic value and contribution rate of each component
成分 特征值 贡献率/% 累积贡献率/% 1 3.968 36.074 36.074 2 2.900 26.367 62.441 3 1.784 11.424 73.865 4 1.097 9.970 83.835 5 0.826 8.243 92.078 6 0.577 5.881 97.958 7 0.218 1.978 99.936 8 0.004 0.035 99.971 9 0.002 0.017 99.988 10 0.001 0.100 99.998 11 0.0007 0.002 100.000 表 5 主成分系数矩阵数值
Table 5. Numerical value of coefficient matrix of principal component
指标 成分 1 2 3 4 含水率/% 0.281 -0.064 -0.056 0.146 密度/g·cm-3 0.076 0.272 -0.017 0.023 干密度/g·cm-3 -0.086 0.337 0.016 -0.075 孔隙比 0.086 -0.336 -0.013 0.063 饱和度/% 0.200 0.142 -0.038 0.098 塑性指数 -0.019 -0.051 -0.173 0.731 液性指数 0.268 -0.057 0.134 -0.044 含水比 0.271 -0.046 0.003 -0.093 压缩系数/MPa-1 -0.006 -0.043 0.462 0.124 黏聚力/kPa 0.082 -0.039 0.224 0.497 内摩擦角/(°) 0.069 0.039 0.702 -0.115 表 6 主成分权重值
Table 6. Principal component weight
主成分 X1 X2 X4 权重 0.498 0.364 0.138 -
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