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Time-Dependent Mechanical Behavior of
"Assembly of Crushed Mudstones" Deposit
Masaki Nakano, Toshihiro Noda, Kenji Takagi and Akira
Asaoka
ABSTRACT : In order to
comprehend the time-dependent mechanical behavior of assembly of crushed
mudstones, constant strain rate consolidation tests, strain controlled
undrained compression tests and undrained creep tests are carried out.
The new findings from these tests are as follows: (1) In constant strain
rate consolidation tests, when void ratios are same, the consolidation
behavior exhibits higher vertical stresses than at slow rate due to
slaking of mudstone pebbles. (2) In strain controlled undrained
compression tests, the undrained shear behavior under rapid rate shows
higher deviator stress than in the slow rate at same axial strain
levels. This is due to slaking of mudstone pebbles. (3) Due to slaking
of mudstone pebbles the undrained creep tests show progressive failure
even under constant load which is less than the peak strength. (4) The
stress response under uniform deformation field for undrained shear
tests are computed using constitutive equation of the Superloading
Cam-clay model. Undrained shear behavior at rapid rates can be simulated
taking the degradation parameter of soil structure m* in
evolution law be small. Conversely, the behav- ior at slow rates can be
simulated taking m* be large.Key words: constitutive
equation, mud stone, slaking, soil structure, time effect, triaxial
test (IGC: D6)
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