In the bedload movement process, coarse sand tended to stay on the sand bar, find sand was brought away.

底沙运动过程中粗粒沙滞留在沙洲，细粒沙被搬走。

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At the contact point of concrete, intensify the movement of vibrator, but not so fast, otherwise coarse aggregate will submerged and separated.

在砼前后接槎处，加强振捣，但也不能过度振捣以防砼发生粗骨料下沉和分层离析。

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