A two-surface viscoplastic model for saturated clays

(1)

[1] Y.J. Cui, T.T. Le, A.M.Tang, P. Delage, X.L. Li. Investigating the time dependent behaviour of Boom clay under thermo-mechanical loading. Géotechnique, 59 (4): 319-329, 2009. [2] L. Šuklje. The analysis of the consolidation process by the isotache method. In: Proc. 4th Int. Conf. on Soil Mech. and Found. Engng., London, vol. 1: 200–206,1957.

1 _{P. Y. Hong , hongp@cermes.enpc.fr}

A two-surface viscoplastic model for saturated clays

P. Y. Hong

1

,Y. J. Cui, J. M. Pereira, A. M. Tang, ENPC, France

F. Collin, University of Liège, Belgium

X.L. Li, ESV EURIDICE GIE , Belgium

X. Sillen, ONDRAF/NIRAS, Belgium

Brussels 2015 - Poster No. P-09-07

Study realised for:

Study description

Experimental tests show that time dependent behavior is significant in Boom Clay [1]. An appropriate model of viscoplasticity is developed for Boom Clay to assess its impact on the long term evolution of the disposal facility.

Results

Constitutive models

Yield surfaces : Hardening law:

p v

p

 



 

2/ 2 2 2 2 2

0

1

f k f f IYS c f c f

M

_p

M

p

f

q

p

k

rp

r

k















_

_









_

_



with: 0 cref vp _IYS v p p q

g

p





__ _ 









IYS YS 0 0

(1

)

vp v cref cref vp v

v

dp

p

v

dr

s

r d

d

 



 





_



















(p'- q) plane: plane

Dilation ratio: 2 2 vp g v vp s g

M

d

k











Isotropic compression tests at different strain rates:

Isotropic compression test including a creep stage on Boom Clay:

Drained triaxial tests on Boom Clay:

-The model can describe the time effects

on the mechanical behavior (viscosity);

-The model can also describe some

important features of natural clays

evidenced experimentally such as the

limited elastic zone, the smooth transition

from elastic to viscoplastic behavior.

Undrained triaxial tests on Boom Clay:

cref cref

p

r





