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The ratio of crack initiation stress to the uniaxial compressive strength (SCI,B/SUC,B) and the ratio of axial strain at the crack initiation stress to the axial strain at the uniaxial compressive strength (UC,BCI,BA,A,/SSSS) were studied by performing numerical stress analysis on blocks having multi flaws at close spacing’s under uniaxial loading using PFC3D. The following findings are obtained:SCI,B/SUC,B has an average value of about 0.5 with a variability of ± 0.1. This range agrees quite well with the values obtained by former research. For joint inclination angle,β=90°,UC,BCI,BA,A,/SSSS is found to be around 0.48 irrespective of the value of joint continuity factor,k. No particular relation is found betweenUC,BCI,BA,A,/SSSS andβ; however, the average UC,BCI,BA,A,/SSSSseems to slightly decrease with increasingk. The variability ofUC,BCI,BA,A,/SSSS is found to increase withk. Based on the cases studied in this work,UC,BCI,BA,A,/SSSS ranges between 0.3 and 0.5.This range is quite close to the range of 0.4 to 0.6 obtained forSCI,B/SUC,B. The highest variability of ± 0.12 forUC,BCI,BA,A,/SSSS is obtained fork=0.8. For the remainingk values the variability ofUC,BCI,BA,A,/SSSS can be expressed within ± 0.05. This finding is very similar to the finding obtained for the variability ofSCI,B/SUC,B.