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STUDY ON THIXOTROPIC PROPERTIES OF TIANJIN SOFT CLAY
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摘要: 软黏土的触变性对于实际工程设计和施工具有重要意义。为了分析天津地区软黏土触变性，本文基于正交试验研究了含水率、矿粉含量和pH值对其十字板强度和触变强度比率等指标的影响。试验结果表明：影响天津软黏土触变强度比率的主次因素依次为含水率、矿粉含量、pH值；软黏土的触变强度比率随含水率的增大而呈指数增大；随矿粉含量增大而呈接近线性减小；随pH值的增大而增大，但其增加幅度逐渐降低，且碱性比酸性环境更有利于软黏土强度的恢复；通过回归分析，建立了包含含水率、矿粉含量、pH值3个因素的天津软黏土触变强度比率预测公式，据此预测触变强度，预测结果较好。研究成果能够为工程实践提供理论参考。Abstract: The thixotropy of soft clay is of great significance for engineering design and construction. In order to analyze the thixotropy of soft clay in Tianjin area,this paper studies the influence of water content,mineral powder content and pH value on the strength and thixotropic strength ratio of the cross plate based on the orthogonal experiment. The test results show that water content,mineral powder content and pH value are the primary and secondary factors affecting the thixotropic strength ratio of Tianjin soft clay. The thixotropic strength ratio of soft clay increases exponentially with the increase of water content, decreases almost linearly with the increase of mineral powder content, and increases with the increase of pH value. But the increasing range gradually decreases. Alkaline is more conducive to the recovery of soft clay strength than acidic environment. By means of regression analysis,a prediction formula for the thixotropic strength ratio of Tianjin soft clay is established. The formula includes water content,mineral powder content and pH value,and predicts the thixotropic strength. The prediction results are better. The research results can provide theoretical reference for engineering practice.
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Key words:
- Soft clay /
- Thixotropy /
- Mineral powder content /
- pH value /
- Thixotropic strength ratio
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图 1 触变强度比率极差值与静置时间关系图
Figure 1. The relationship between the thixotropic intensity ratio range and the resting time
图 2 十字板剪切强度与含水率关系
Figure 2. The relationship between shear strength of cross plate and moisture content
图 3 触变强度比率A与含水率关系
Figure 3. Relationship between thixotropic strength ratio A and water content
图 4 十字板剪切强度与矿粉含量关系
Figure 4. The relationship between the shear strength of cross plate and the content of mineral powder
图 5 触变强度比率A与矿粉含量的关系
Figure 5. Relationship between thixotropic strength ratio A and mineral powder content
图 6 十字板剪切强度与pH值关系
Figure 6. The relationship between cross plate shear strength and pH value
图 7 触变强度比率A与pH值的关系
Figure 7. Relationship between thixotropic strength ratio A and pH value
表 1 天津软黏土基本物性指标
Table 1. Basic physical property index of Tianjin soft clay
孔隙比e 含水率ω/% 密度ρ/g·cm-3 相对密度Gs 液限WL/% 塑限Wp/% 塑性指数Ip 液性指数IL 压缩系数av/MPa-1 压缩模量Es/MPa pH值 1.20 46.9 1.71 2.76 43.4 22.9 20.5 1.17 0.845 2.605 9.3 
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表 2 天津软黏土的矿物成分
Table 2. Mineral composition of Tianjin soft clay
成岩矿物种类和含量/% 黏土矿物总量/% 石英 钾长石 斜长石 方解石 白云石 黄铁矿 石盐 角闪石 19.0 1.1 8.5 16.2 0.8 0.2 1.4 0.2 52.6
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表 3 石英粉基本物性指标
Table 3. Basic physical properties of quartz powder
液限WL/% 塑限Wp/% 塑性指数Ip 22.4 15.2 7.2
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表 4 正交试验因素水平表
Table 4. Level of orthogonal test factors
水平 因素 ω/% c/% b e1 e2 1 34 0 5.1 1 1 2 36 5 7.0 2 2 3 38 10 9.2 3 3 4 40 15 11.4 4 4 矿粉含量为掺入矿粉与干土的百分比
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表 5 正交试验结果
Table 5. Results of orthogonal experiments
组数 因素 触变强度比率A ω/% c/% b e1 e2 5 h 1 d 7 d 14 d 28 d 60 d A1 34 0 5.1 1 1 1.112 1.350 1.665 1.889 2.078 2.248 A2 34 5 7.0 2 2 1.102 1.328 1.620 1.831 2.018 2.185 A3 34 10 9.2 3 3 1.104 1.292 1.554 1.749 1.935 2.098 A4 34 15 11.4 4 4 1.087 1.254 1.497 1.683 1.873 2.038 A5 36 0 7.0 3 4 1.175 1.419 1.738 1.966 2.159 2.332 A6 36 5 5.1 4 3 1.091 1.311 1.608 1.823 2.014 2.184 A7 36 10 11.4 1 2 1.158 1.355 1.629 1.834 2.029 2.200 A8 36 15 9.2 2 1 1.075 1.240 1.480 1.664 1.852 2.015 A9 38 0 9.2 4 2 1.265 1.597 1.993 2.276 2.494 2.728 A10 38 5 11.4 3 1 1.256 1.569 1.948 2.222 2.445 2.681 A11 38 10 5.1 2 4 1.078 1.343 1.675 1.921 2.135 2.357 A12 38 15 7.0 1 3 1.070 1.306 1.608 1.836 2.048 2.265 A13 40 0 11.4 2 3 1.401 1.942 2.525 2.940 3.222 3.605 A14 40 5 9.2 1 4 1.311 1.798 2.325 2.705 2.977 3.339 A15 40 10 7.0 4 1 1.203 1.636 2.113 2.464 2.732 3.081 A16 40 15 5.1 3 2 1.108 1.494 1.928 2.252 2.517 2.853
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表 6 触变强度比率方差分析
Table 6. Thixotropic strength ratio analysis of variance
方差来源 平方和Si 自由度fi Fi值 显著性 含水率 1.647 3 18.8 显著 矿粉含量 0.382 3 4.36 pH值 0.090 3 1.00
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表 7 参数取值
Table 7. Parameter value
组别 k m At-∞ R2 A1 -1.043 05 11.983 05 2.223 09 0.997 27 A2 -0.991 17 12.628 52 2.166 42 0.999 77 A3 -0.928 45 13.627 06 2.087 59 0.993 68 A4 -0.899 77 14.734 40 2.036 32 0.997 89 A5 -1.061 56 11.975 73 2.306 79 0.996 94 A6 -1.009 81 12.640 20 2.165 20 0.999 77 A7 -0.973 72 13.639 20 2.189 73 0.993 58 A8 -0.889 49 14.747 13 2.013 35 0.997 79 A9 -1.319 72 11.659 48 2.684 69 0.997 22 A10 -1.292 81 12.270 55 2.644 74 0.999 65 A11 -1.172 41 13.182 22 2.332 86 0.993 98 A12 -1.105 70 14.123 90 2.250 66 0.997 28 A13 -1.947 50 11.291 10 3.518 59 0.993 31 A14 -1.799 68 11.813 13 3.267 20 0.995 05 A15 -1.679 51 12.626 08 3.024 84 0.998 72 A16 -1.573 46 13.470 06 2.811 43 0.992 43
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表 8 Fi检验结果表
Table 8. Fi test result table
参数 自由度 剩余自由度 置信度 临界值 检验值 相关系数R2 k 7 8 95% 3.500 6.98 0.9996 m 9 6 95% 4.099 6.22 0.9997 At-∞ 7 8 95% 3.500 5.44 0.9983
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