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(B,UCB,CI,A,A...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(B,UCB,CI,A,A/SSSS) were studied by performing numerical stress analysis on blocks having multi flaws at close spacing's under uniaxial loading using PFC3 D. 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°,B,UCB,CI,A,A/SSSS is found to be around 0.48 irrespective of the value of joint continuity factor, k. No particular relation is found betweenB,UCB,CI,A,A/SSSS and β; however, the average B,UCB,CI,A,A/SSSS seems to slightly decrease with increasing k. The variability ofB,UCB,CI,A,A/SSSS is found to increase with k.Based on the cases studied in this work,B,UCB,CI,A,A/SSSS ranges between 0.3 and 0.5. This range is quite close to the range of 0.4to 0.6 obtained for SCI,B/SUC,B. The highest variability of ± 0.12 forB,UCB,CI,A,A/SSSS is obtained for k=0.8. For the remaining k values the variability ofB,UCB,CI,A,A/SSSS can be expressed within ± 0.05. This finding is very similar to the finding obtained for the variability of SCI,B/SUC,B.展开更多
We investigated the combined influence of joint inclination angle and joint continuity factor on deforma- tion behavior of jointed rock mass for gypsum specimens with a set of non-persistent open flaws in uni- axial c...We investigated the combined influence of joint inclination angle and joint continuity factor on deforma- tion behavior of jointed rock mass for gypsum specimens with a set of non-persistent open flaws in uni- axial compression. Complete axial stress-strain curves were classified into four types, i.e., single peak, softening after multi-peak yield platform, hardening after multi-peak yield platform and multi-peak dur- ing softening. Observation of crack evolution on the specimen surface reveals that the deformation behavior is correlated to the closure of pre-existing joint, development of fractures in rock matrix and teeth shearing of the shear plane. To investigate the brittleness of the specimens, the ratio of the residual strength to the maximum peak strength as well as the first and last peak strains were studied. At the same joint inclination angle, the ratios between residual strength and the maximum peak strength and the last peak strains increased while the first peak strain decreased with the increase of joint continuity factor. At the same joint continuity factor, the curves of the three brittleness parameters vs. joint inclina- tion angle can either be concave or convex single-oeak or wave-shaoed.展开更多
基金Project(11102224)supported by the National Natural Science Foundation of ChinaProject(201206370124)supported by the China Scholarship Council,China
文摘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(B,UCB,CI,A,A/SSSS) were studied by performing numerical stress analysis on blocks having multi flaws at close spacing's under uniaxial loading using PFC3 D. 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°,B,UCB,CI,A,A/SSSS is found to be around 0.48 irrespective of the value of joint continuity factor, k. No particular relation is found betweenB,UCB,CI,A,A/SSSS and β; however, the average B,UCB,CI,A,A/SSSS seems to slightly decrease with increasing k. The variability ofB,UCB,CI,A,A/SSSS is found to increase with k.Based on the cases studied in this work,B,UCB,CI,A,A/SSSS ranges between 0.3 and 0.5. This range is quite close to the range of 0.4to 0.6 obtained for SCI,B/SUC,B. The highest variability of ± 0.12 forB,UCB,CI,A,A/SSSS is obtained for k=0.8. For the remaining k values the variability ofB,UCB,CI,A,A/SSSS can be expressed within ± 0.05. This finding is very similar to the finding obtained for the variability of SCI,B/SUC,B.
基金supported by the National Natural Science Foundation of China (No. 11102224)the Fundamental Research Funds for the Central Universities of China(No. 2009QL05)
文摘We investigated the combined influence of joint inclination angle and joint continuity factor on deforma- tion behavior of jointed rock mass for gypsum specimens with a set of non-persistent open flaws in uni- axial compression. Complete axial stress-strain curves were classified into four types, i.e., single peak, softening after multi-peak yield platform, hardening after multi-peak yield platform and multi-peak dur- ing softening. Observation of crack evolution on the specimen surface reveals that the deformation behavior is correlated to the closure of pre-existing joint, development of fractures in rock matrix and teeth shearing of the shear plane. To investigate the brittleness of the specimens, the ratio of the residual strength to the maximum peak strength as well as the first and last peak strains were studied. At the same joint inclination angle, the ratios between residual strength and the maximum peak strength and the last peak strains increased while the first peak strain decreased with the increase of joint continuity factor. At the same joint continuity factor, the curves of the three brittleness parameters vs. joint inclina- tion angle can either be concave or convex single-oeak or wave-shaoed.
