According to the coal sample's pore fractal laws, the porosity of coal is divided into three categories: infiltration pore, diffusion pore and adsorption pore.

这三类孔同时也对应了瓦斯等气体在煤中的不同的运移状态。

youdao

Coal mining and other mining enterprises of various categories must update hydrological and geological data about their mine shafts to guard against water inrush or inundation.

要求煤矿和其它各类矿山企业，都要健全矿井水文地质资料，严防发生透水、淹井事故。

youdao

A strategic storage system of coal resources shall be established, and protective exploitation shall be conducted to the special and rare coal categories.

建立煤炭资源战略储备制度，对特殊和稀缺煤种实行保护性开发。

youdao