ABSTRACT
The post-failure behaviour of pillar models was monitored on dolente rock samples. Compression tests were conducted to determine the effect of width to height ratio on the failure process. A servo-controlled, stiff INSTRON testing machine was used to uniaxially load specimens with width to height ratios within the range of 0.5 to 4.0.
The results showed that post-failure behaviour is dependant on geometry of pillars. It was found that as width to height ratio increases, the mode of failure changes from sudden, rapid reduction of stress bearing capacity through the formation of large axial fractures and shearing, to progressive change of compressive strength. This is associated with the formation of concentric fractures around the pillar periphery. It was also found that the pillar geometry affects the value of Young’s modulus and the value of failure strain of rock samples.
