Beneath this active layer is a second layer called "permafrost", which is frozen all year around, and is impermeable to water.

在这一活跃层下面，是被称为“多年冻土”的第二层，终年冻结，不透水。

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Particularly, the solution for impermeable silt-layer can be used to describe the tidal fluctuation in a confined aquifer under a tidal river separated by an impermeable layer.

特别地，当边界淤泥层为隔水层时，本文的解也可用来描述有潮河流下的承压含水层中的水头波动情况。

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When confined aquifer under the bottom of the pit, the foundation excavation will reduce the thickness of overlying impermeable layer.

在基坑底部以下存在承压水层的情况下，基坑开挖减少含水层上覆不透水层的厚度。

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Landfills without the benefit of a naturally impermeable layer use plastic liners and imported clay.

ECONOMIST: The charms of modern landfills

He says the Bakken has a layer of nearly impermeable shale that sits above the oil-bearing reservoirs.

FORBES: Focus