Abstract:

The short-time rheology tests of No.3 coal seam of a Shandong colliery was carried out with MTS815 servo-controlled rock mechanical test system; the creep model and failure characteristics were analyzed. The experimental results indicate that the coal’ creep threshold coefficient is 0.915 and its rheological coefficient is 0.383; rheological failure of coal presents spatial inhomogeneity, plastic destroying is mostly as a whole but dominant failure plane orientation is sheared failure; mirco-ruptures occur in the rheological process of coal which is damage; and furthermore those damages occur on lower stress levels, just the accumulation and transfixion of lots of micro-ruptures induce the failure of coal sample; both damage and hardening exist in coal creep, the creep process lies on those two mechanisms; three polynomial experiential model can describe creep characteristics of this coal compatibly; and Nishihara model can describe its initial creep stage and steady creep stage, but not accelerating creep stage.

Key words: coal, short-time rheological test, failure character, micro-rupture, creep model