Unstable Behaviour of a Sand Cap Placed over a Weak Sensitive Clay Deposit
CEDA Dredging Days 2019
M. Martinelli, D. Luger, A. Talmon and V. Galavi
Abstract: Sand capping is an accepted method to create containment of soft (often contaminated) deposits that may consist of e.g. dredged harbor sediments or mine tailings. The low strength that many of these deposits have forces the contractors to work very carefully since uneven placement of sand, or local weakness in the deposit, can trigger failures that severely hamper the further placement of the sand cap.
A constitutive model was used which captures softening and rate dependent behavior of the deposit. The computer code, in which the model is implemented, is based on the Material Point Method (MPM) and it is especially suited to handle large strains and displacements. These capabilities are essential in the modelling of local plunging failure of part of the sand cap and its sinking into the soft deposit.
Such instabilities have been observed in the field but they are not yet realistically simulated by numerical analyses. The paper shows the effect of different strain softening characteristics and viscous parameters of the soft deposit.
Keywords: Sand capping, hydraulic fill, sensitive clay, MPM