Road Embankments on Seasonally-Frozen Peat Foundations
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Date
2014-09, 2014-09, 2014-09, 2013-09, 2013-09
Authors
De Guzman, Earl Marvin
Journal Title
Journal ISSN
Volume Title
Publisher
Canadian Geotechnical Society - Proceedings of the 67th Canadian Geotechnical Conference
International Association of Lowland Technology
Canadian Geotechnical Society - Proceedings of the 66th Canadian Geotechnical Conference
International Association of Lowland Technology
Canadian Geotechnical Society - Proceedings of the 66th Canadian Geotechnical Conference
Abstract
Muskeg or peat deposits cover large areas in northern Manitoba. Test sections of a newly constructed highway on peat were instrumented to investigate their performance and to develop more economical means of construction method. Test Section ‘A’ was constructed with geotextile base layer while Section ‘B’ was with geotextile and corduroys (timber logs). The test sections were constructed during winter for ease in mobilizing construction equipment at the site when the ground was frozen and were instrumented to observe its behaviour and performance. Settlements were measured using monitoring plates and pins. Ground temperatures were measured using thermistors. Porewater pressures were measured using vibrating wire piezometers.
Peat in the study area has an average thickness of 4m, with the upper layer classified as fibrous and the lower layer as amorphous with strong to complete decomposition. Standard laboratory tests were conducted on bored samples from the site. Hydraulic conductivity tests were carried out at different vertical pressures to determine its permeability. Thermal conductivity was determined at frozen and unfrozen state of peat. Conventional incremental oedometer tests were conducted to determine the compressibility parameters and secondary compression indices of the peat layers. Constant-rate-of-strain (CRS) tests were also performed to supplement the results obtained from the conventional method. Isotropically-Consolidated Undrained (CIŪ) triaxial tests were carried out to determine the shear strength of peat.
A commercially-available computer program was used in the numerical modelling to simulate the field performance of the instrumented sections. The results from numerical modelling were reasonably close to the measured values in the field. Laboratory-scale physical modelling was undertaken to understand further the operating mechanisms involved in the performance of the two test sections under a more controlled environment. Artificial transparent clay that has similar deformation properties with most of the natural clays and peats was used as foundation material. It allows determination of spatial deformations beneath the embankment using Particle Image Velocimetry (PIV) technique. The load-settlement behaviour in the field was also reasonably simulated in the laboratory-scaled physical model. Deformation patterns from PIV indicate that embankment with geotextile layer and corduroy has smaller settlements and lateral movements in the foundation compared to that of the embankment with only geotextile layer.
Description
Keywords
peat, seasonally-frozen ground, road embankments, laboratory testing, numerical modelling, physical modelling
Citation
De Guzman, E.M.B. and Alfaro, M.C. 2014. Numerical and Physical Modelling of Road Embankments on Seasonally-Frozen Peat. 67th Canadian Geotechnical Conference. Regina, SK.
De Guzman, E.M.B. and Alfaro, M.C. 2014. Utilization of Local Timber Logs in Highway Embankment Construction. International Symposium on Woods Utilization. Saga, Japan.
De Guzman, E.M.B. and Alfaro, M.C. 2014. Characterization of Peat in Northern Manitoba, Canada. 9th International Symposium on Lowland Technology. Saga, Japan.
De Guzman, E.M.B. and Alfaro, M. 2013. Performance of Highway Embankment on Peat Deposits Constructed under Winter Conditions. 66th Canadian Geotechnical Conference. Montreal, QC.
De Guzman, E.M.B. and Alfaro, M. 2013. Engineering Characteristics of Peat Deposits in Northern Manitoba. 66th Canadian Geotechnical Conference. Montreal, QC.
De Guzman, E.M.B. and Alfaro, M.C. 2014. Utilization of Local Timber Logs in Highway Embankment Construction. International Symposium on Woods Utilization. Saga, Japan.
De Guzman, E.M.B. and Alfaro, M.C. 2014. Characterization of Peat in Northern Manitoba, Canada. 9th International Symposium on Lowland Technology. Saga, Japan.
De Guzman, E.M.B. and Alfaro, M. 2013. Performance of Highway Embankment on Peat Deposits Constructed under Winter Conditions. 66th Canadian Geotechnical Conference. Montreal, QC.
De Guzman, E.M.B. and Alfaro, M. 2013. Engineering Characteristics of Peat Deposits in Northern Manitoba. 66th Canadian Geotechnical Conference. Montreal, QC.