A loss of the overall resistance of samples of rocks or “stiff” soils is frequently observed during compression tests, after a peak load level has been reached. This particular behaviour, which is customarily referred to as strain softening, in most cases shows up together with the localization of strain within narrow bands in which the non reversible deformation attains values much higher than those reached in the adjacent portions of the sample (Han and Drescher, 1993). In the following, the experimental aspects of the phenomenon are outlined first, considering in particular the results of plane strain compression tests. Then, the closed form solution of a simple problem is discussed concerning the influence of a non associated flow rule on the onset of softening. Finally, the results of some finite element analyses are presented accounting for strain softening effects. They refer to the stability of a cantilever sheet wall and of a shallow tunnel in a frictional material. The results of calculations permit to draw some conclusions on the characteristics of the adopted numerical technique and on its applicability to actual engineering problems.
Strain softening effects in the numerical analysis of geotechnical problems
STERPI, DONATELLA VALERIA;CIVIDINI, ANNAMARIA;GIODA, GIANCARLO
1998-01-01
Abstract
A loss of the overall resistance of samples of rocks or “stiff” soils is frequently observed during compression tests, after a peak load level has been reached. This particular behaviour, which is customarily referred to as strain softening, in most cases shows up together with the localization of strain within narrow bands in which the non reversible deformation attains values much higher than those reached in the adjacent portions of the sample (Han and Drescher, 1993). In the following, the experimental aspects of the phenomenon are outlined first, considering in particular the results of plane strain compression tests. Then, the closed form solution of a simple problem is discussed concerning the influence of a non associated flow rule on the onset of softening. Finally, the results of some finite element analyses are presented accounting for strain softening effects. They refer to the stability of a cantilever sheet wall and of a shallow tunnel in a frictional material. The results of calculations permit to draw some conclusions on the characteristics of the adopted numerical technique and on its applicability to actual engineering problems.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
