The cushion layer for the dam is constructed with the material prepared mainly with natural sandy gravel and mixed with proper amount of pebble and coarse sand.

大坝垫层料采用以天然砂砾料为主、掺入小石和粗砂以调整级配的方式生产。

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Although feet were designed to walk barefoot on Earth's natural surfaces (grass, sand or gravel), they were not prepared to endure the concrete, asphalt and steel that covers so many landscapes today, Thompson said.

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Nothing has prepared me for the view: a vast valley of black gravel sweeps into the distance under a sapphire sky.

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