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| End friction effect of Mogi type of true-triaxial test apparatus |
| FAN Pengxian，LI Ying，ZHAO Yuetang，DONG Lu，MA Linjian |
(State Key Laboratory of Disaster Prevention and Mitigation of Explosion and Impact，Army University of Engineering，
Nanjing，Jiangsu 210007，China)
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Abstract Due to the rigid platens used in Mogi type of true-triaxial test apparatus，the friction between the loading platens and samples enhances the measured strength of material. In order to quantitatively estimate the end effect，the biaxial compression tests on the red sand stone samples were conducted under different interface frictions and intermediate stress conditions. The measured strengths of samples under different interface frictions differ significantly. When the friction coefficients of interface increase from 0.12 to 0.28，the maximum stresses of samples under the same intermediate stress increase 5.5% to 43%. Several yielding criteria were used to estimate the end effect and the strain energy criterion was adopted for further analysis. An expression for end effect was established and the intermediate stress effect curves considering end effect were drawn in coordinate. The influence of end friction on the curve?s shape was revealed to agree well with test results.
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2017, Vol. 36 
