Methodology for horizontal gravel pack wells in Brazilian deepwater. 巴西深水域中水平礫石充填井的方法。
In drainage of agricultural lands, a filter or gravel envelope is used to prevent the entrance of fine sand and silt into the drains. 在農田排水中常常採用礫石或過濾層來防止粉細砂和泥沙進入排水溝。