scholarly journals Effects of Piston Uplift, Piston Friction, and Machine Deflection in Reduced Triaxial Extension Testing

Author(s):  
Morgan L. Race ◽  
Richard A. Coffman
Keyword(s):  
Geosciences ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 29 ◽  
Author(s):  
Zenon Szypcio

The strength of sand is usually characterized by the maximum value of the secant friction angle. The friction angle is a function of deformation mode, density, and stress level and is strongly correlated with dilatancy at failure. Most often, the friction angle is evaluated from results of conventional compression tests, and correlation between the friction angle of sand at triaxial compression and triaxial extension and plane strain conditions is a vital problem of soil mechanics. These correlations can be obtained from laboratory test results. The failure criteria for sand presented in literature also give the possibility of finding correlations between friction angles for different deformation modes. The general stress-dilatancy relationship obtained from the frictional state concept, with some additional assumptions, gives the possibility of finding theoretical relationships between the friction angle of sand at triaxial compression and triaxial extension and plane strain conditions. The theoretically obtained relationships presented in the paper are fully consistent with theoretical and experimental findings of soil mechanics.


2011 ◽  
Vol 243-249 ◽  
pp. 2183-2187
Author(s):  
Jun Xin Liu ◽  
Zhong Fu Chen ◽  
Wei Fang Xu

For soils, failure occurs with lower deviatoric stress under the same pressure (the first invariant of stress tensor) in TXE compared with the strength of the triaxial compression, which is indicated that the strength of soils strongly depends on the third invariant of stress deviator; Although in the traditional Mohr-Coulomb criterion it can be reflected in difference of strength between triaxial extension and compression under the same pressure, it’s nothing to do with the pressure for the strength ratio between triaxial extension and compression. By TXC and TXE, changes of deviatoric stress and the ratio with the pressure were studied


2008 ◽  
Vol 45 (4) ◽  
pp. 574-587 ◽  
Author(s):  
Scott M. Olson ◽  
Benjamin B. Mattson

A database of 386 laboratory triaxial compression, direct simple shear, rotational shear, and triaxial extension test results was collected to examine yield and liquefied strength ratio concepts used in liquefaction analysis of sloping ground. These data envelope the yield and liquefied strength ratios obtained from back-analyses of liquefaction flow failure case histories. Generally, triaxial compression exhibits the highest yield and liquefied strength ratios, triaxial extension yields the lowest ratios, and direct simple shear – rotational shear shows intermediate responses. However, mode of shear appears to have a considerably smaller effect on laboratory-measured liquefied strength ratios for specimens with a positive state parameter (i.e., difference in consolidation void ratio and steady state void ratio at the same effective stress).


2011 ◽  
Vol 250-253 ◽  
pp. 2089-2092
Author(s):  
Rong Jian Li ◽  
Xi An Li ◽  
Gao Feng Che ◽  
Wen Zheng ◽  
Wen Jun Chen

Stress path is one of the very important factors of soil strength. It is significant to study the strength and reveal the importance of the impact of sand in different stress path conditions. Firstly, an ameliorating approach on implementing for the reduced triaxial extension by the conventional triaxial apparatus was discussed. Then, In order to study shear behaviors of the eolian sand under different stress path, two monotonic shearing tests with the conventional triaxial compression and the reduced triaxial extension stress path were performed and analyzed. The test results not only indicate that the amelioration on conventional triaxial apparatus is simple, practicable and inexpensive, but also reveal the difference of strength’s parameter between the reduced triaxial extension and conventional triaxial compression stress path. In sum, the stress path has important effect on the strength of the eolian sand.


2019 ◽  
Vol 59 (5) ◽  
pp. 1399-1416 ◽  
Author(s):  
Razvan Ignat ◽  
Sadek Baker ◽  
Martin Holmén ◽  
Stefan Larsson

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