In the drivage of the coal drift in the Zhangji coal mine, most of the coal drift is revealed to be composite roof.

• 在中厚煤层复合顶板条件下,合理确定小煤柱尺寸及巷道支护参数,可提高煤炭回收率,保证巷道正常掘进和在服务期间内的使用。