A STUDY OF PEAT SAMPLE PARAMETERS INFLUENCE ON SETTLEMENT DURING COMPRESSION TESTING AND NUMERICAL SIMULATION

References: 17th International Multidisciplinary Scientific GeoConference SGEM 2017, www.sgem.org, SGEM2017 Conference Proceedings, ISBN 978-619-7105-99-5 / ISSN 1314-2704, 29 June - 5 July, 2017, Vol. 17, Issue 12, 651-658 pp, DOI: 10.5593/sgem2017/12/S02.083

ABSTRACT

The reliability of forecasted long-term peat settlement under embankment is primarily determined not by the soil models used, but by the specific features of peat laboratory testing. This article presents the results of oedometer tests of various-height peat samples with squeezing of pore water towards only top or top and bottom faces. The load was applied to the samples in two ways: by gradual stepwise increase or all at once. The stabilization condition for each load was sample deformation not exceeding 0.01 mm per day. The duration of some experiments reached several months.
The experiments have shown that the deformations of samples 30, 50 and 70 mm in height under the same draining conditions differ by 8-16% due to the effect of peat friction against the oedometer walls. The final peat settlement depends only on the value of load, and the influence of load application method and direction of pore water squeezing is insignificant. These factors determine the duration of deformation development. For example, the settlement rate with top face pore water filtration was 25…40 % below in comparison with two faces filtration.
The impact of model input parameters onto the process of long-term peat settlement was evaluated also by numerical simulation of oedometer tests in PLAXIS 3D software. As a result a method of reducing the duration of peat testing was proposed.

Keywords: peat, settlement, deformation, oedometer tests.