Abstract: The test device and method on the water conduction coefficient for large sample under triaxial stress state are introduced. The tested results from the 18 coal seams in China have made known that the water conduction coefficients of the coal masses are attenuating in minus exponential law with the volume stress increasing, and increasing in positive exponential law with pore water pressure increasing. In statistical sense, the water conduction coefficients of the coal masses are interrelated with the coal metamorphic grade. But they are also influenced by the geological and structural conditions of the coal seams. It should be based on the test to evaluate coal seam permeability. The study results are of some guide meaning for coal seam infusion, gas suction and coal gas exploitation.

Key words: large sample, triaxial stress, water conduction coefficient, test in laboratory