Home / Standards / GB/T 23561.4-2009 GB/T 23561.4-2009 Active Methods for determining the physical and mechanical properties of coal and rock - Part 4: Methods for calculating the porosity of coal and rock 煤和岩石物理力学性质测定方法 第4部分：煤和岩石孔隙率计算方法 Standard Type GBT ICS 73.010 CCS D04 Status 现行 Issue Date 2009-04-08 Implementation 2009-12-01 Responsible Dept 中国煤炭工业协会 Drafting Unit 中国煤炭工业协会