Abstract: Fractured rock mechanics behavior is the foundation of underground engineering stability analysis. Experimental study on strength degradation and the loading rate effect of sandstone containing a lengthways fissure under uniaxial compression has been done based on the mechanics model of roadway roof in the western shallow buried strata. The results show that, split failure will dominantly happen in the samples when the translation distance is small (0-6 mm); while mixed failure of split and shearing will probably occur when the translation distance is large (12-24 mm); and the shearing failure is the decisive factor leading to final instability. With the increasing of fissure translation distance, sample capacity presents a trend of increasing first, then decreasing and gradual increasing again, and the translation distance between 6 mm to 12 mm appears an obvious sudden change region which is closely related to the failure form of the samples. The capacity of sample containing lengthways fissure increases gradually with the increasing of loading rate, however the strength degradation coefficient decreases and presents the staged characteristic of first sharp decline and then gentle variation.

Key words: rock mechanics, roof, lengthways fissure, strength degradation, loading rate effect