THE CALCULATION METHOD FOR OSMOTIC SUCTION OF SALINE SOLUTION
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摘要: 膨润土垫层在高放废料处置库环境中与围岩接触，力学性能会受到围岩裂隙中所含盐溶液的影响。盐溶液的渗透吸力会在膨润土上产生类似于竖向荷载作用的附加应力，量化盐溶液对膨润土力学性能的影响对评估地下处置库的安全性具有重要意义。溶液渗透吸力系数作为计算渗透吸力的关键，目前需要通过较为复杂的实验测得，对工程实际应用造成了阻碍。通过引入Debye-Hückel公式，提出含单价离子电解质、2-2型电解质及混合电解质溶液的渗透吸力系数及渗透吸力的计算方法。基于Debye-Hückel公式，分析溶剂种类和温度对渗透吸力系数的影响，结果表明：溶剂极性越大，渗透吸力系数越大；温度越高，渗透吸力系数越小。
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关键词:
- 膨润土 /
- 盐溶液 /
- 渗透吸力 /
- Debye-Hückel公式
Abstract: When bentonite cushion contacts with surrounding rocks in a disposal repository of highly radioactive waste, its mechanical properties will be affected by the saline solution contained in surrounding rock cracks, and the osmotic suction of salt solution will add additional stress similar to vertical load on bentonite. Therefore, quantifying the effect of saline solution on the mechanical properties of bentonite is of great significance for evaluating the safety of underground repository. Osmotic coefficients as the key to calculate the osmotic suction are usually obtained by complex tests, which obstructs the practical engineering applications. The Debye-Hückel formula are introduced to calculate the osmotic coefficients and osmotic suction for monovalent ion electrolyte, 2-2 type electrolyte and mixed electrolyte solutions. The impact of various factors on solution suction coefficients, such as solvent type, solute type, solute concentration and temperature are analyzed. Then the calculation method of osmotic suctions of different solutions are obtained. Based on the Debye-Hückel formula, the influence of solvent type and temperature on the osmotic suction coefficient is analyzed. The results show that the larger the solvent polarity, the larger the osmotic suction coefficient; the higher the temperature, the smaller the osmotic suction coefficient.-
Key words:
- bentonite /
- saline solution /
- osmotic suction /
- Debye-Hücke formula
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图 1 钠盐在水溶液中渗透吸力系数与溶质浓度关系
Figure 1. Relationship between osmotic suction coefficient and solute concentration for sodium salt in agueous solution
图 2 NaCl和CaCl2的渗透吸力与溶质浓度的关系
Figure 2. Relationship between osmotic suction and solute concentration of NaCl and CaCl2
图 3 三种硫酸盐水溶液中的渗透吸力系数与溶质浓度的关系
Figure 3. Relationship between osmotic suction coefficient and solute concentration for three kinds of sulfate solutions
图 4 NaCl-KCl混合溶液渗透吸力系数与浓度的关系
Figure 4. Relationship between osmotic suction coefficient and concentration for NaCl-KCl mixed solutions
图 5 渗透吸力系数随温度变化关系
Figure 5. Relationship between osmotic suction coefficient and temperature
表 1 不同种类含单价离子电解质的渗透吸力系数
Table 1. Osmotic suction coefficients of different monovalent ionic electrolytes
c(mol/kg) 1-1型 2-1型 3-1型 1-2型 1-3型 1-4型 1-5型 KCl Ca(NO3)2 CaCl2 AlCl3 Na2SO4 K3PO4 Na4P2O7 Na5P3O4 0.01 0.967 0.904 0.907 0.842 0.898 0.819 0.739 0.667 0.05 0.940 0.850 0.864 0.810 0.828 0.738 0.644 0.576 0.1 0.926 0.831 0.856 0.819 0.793 0.708 0.589 0.510 0.2 0.913 0.820 0.862 0.850 0.754 0.680 0.520 0.432 0.3 0.906 0.818 0.876 0.891 0.728 0.667 0.489 0.397 0.4 0.902 0.819 0.895 0.942 0.707 0.662 0.483 0.376 0.5 0.900 0.823 0.916 1.002 0.691 0.661 0.496 - 0.7 0.898 0.836 0.964 1.143 0.665 0.666 - - 1 0.898 0.861 1.048 1.390 0.641 - - - 1.6 0.905 0.917 1.243 1.953 0.622 - - - 2 0.913 0.951 1.386 - 0.624 - - - 2.5 0.924 0.904 1.572 - 0.638 - - - 3 0.937 0.850 - - 0.662 - - - 4 0.965 0.831 - - 0.734 - - - 4.8 0.989 0.820 - - - - - - 
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表 2 不同溶质的渗透吸力系数
Table 2. Osmotic suction coefficients of different solutes
c(mol/kg) MgSO4 ZnSO4 CuSO4 CaSO4 0.001 0.894 0.895 0.888 0.910 0.005 0.791 0.793 0.778 0.792 0.01 0.741 0.741 0.725 - 0.05 0.635 0.623 0.611 - 0.1 0.595 0.573 0.560 - 0.5 0.525 0.482 0.467 - 1 0.527 0.477 0.463 - 1.4 0.562 0.510 0.488 2 0.660 0.606 - - 3 0.913 0.860 - - 3.5 - 1.022 -
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表 3 不同溶质的Debye-Hückel系数
Table 3. Debye-Hückel coefficients of different solvents
溶剂 εr ρsl(kg/m3) A 水 78.4 1000 0.393 甲醇 32.63 786.6 1.297 乙醇 24.35 785 2.009 丙酮 20.7 784.35 2.562 乙酸乙酯 6.02 894.5 17.447 苯 2.28 873.6 73.974
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表 4 水在不同温度中的D-H系数
Table 4. Debye-Hückel coefficients of water under different temperatures
温度/K 相对介电常数εr 参数A 273 87.74 0.3781 278 85.76 0.3808 283 83.83 0.3836 288 81.95 0.3866 293 80.1 0.3899 294 79.73 0.3906 296 79.02 0.3918 298 78.3 0.3933 300 77.6 0.3946 303 76.55 0.3968 308 74.83 0.4006 313 73.15 0.4046 318 71.15 0.4119 323 69.91 0.4131
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