A Calculation Method for Vapor Migration in the Earth's Surface of “the Pot Cover Effect”
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摘要: 地表不透气的覆盖层使土体表面蒸发受阻,引起水分在覆盖层下集聚,导致覆盖层下土体含水率升高的现象被称为"锅盖效应"。" "锅盖效应" "会引起一系列的工程病害。目前在计算"锅盖效应"水汽迁移量时,大多采用多场耦合的数值计算方法,计算繁琐不便于使用。根据工程实际条件,推导并得到了可以预测不同埋深位置土体温度的计算式;基于Fick定律,推导得出能反映气态水迁移量的计算式;进而提出一种简单的"锅盖效应"水汽迁移量计算方法。对该计算方法得到的计算值与现场试验的实测值对比显示,变化趋势较为接近;表明该方法能够反映出土体不同埋深位置含水率变化趋势,有效、可行。Abstract: Pot cover effect refers to the phenomenon that moisture accumulates underneath an airproof cover in the earth's surface. "Pot cover effect" may lead to a high moisture content in soil under the cover and induce engineering disasters. At present, numerical simulations of multi-field coupling are mostly used in the calculation for vapor migration, the processes of calculations are tedious and inconvenient. Accordingto the actual engineering conditions, the calculation formula for temperature at different depth was deduced. Based on the Fick’s law, the formula for calculating the amount of vapor migration was inferred. By combining the above formulas, a simple calculation method of vapor migration on "pot cover effect" was proposed. The calculated values were compared with the measured values. The results showed that the calculation method could reflect the trend of vapor migration in the earth at different depths. The calculation method was effective and feasible.
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Key words:
- pot cover effect /
- vapor /
- moisture content /
- fick's law
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