In drainage of agricultural lands, a filter or gravel envelope is used to prevent the entrance of fine sand and silt into the drains.
在农田排水中常常采用砾石或过滤层来防止粉细砂和泥沙进入排水沟。
The ground stratum is quite complex, with silt layer and fine sand layer mixed, so the construction is difficult to be carried out and the requirement of pit support is strict.
基坑所处地层十分复杂，有较厚的淤泥层和细砂层，基坑支护要求高，施工难度大。
In column experiment the salt release flux from different sediment can be expressed as a negative exponential function and decrease in the order of silty clay, medium-fine sand and pelitic silt.
静水实验中沉积物向上覆水体盐分释放通量符合负的幂指数形式，并按粉质粘土、中细砂、泥质粉砂顺序递减；
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