Load transfer of pile foundations in frozen and unfrozen soft clay

This paper investigates load-carrying capacity of two conventional and three helical piles in frozen soft clay and evaluates the changes in pile capacity corresponding to ground thawing. In-situ pile load tests were conducted in frozen and unfrozen Leda clay and used to establish stress-strain correlations to describe the load transfer of the test piles. The stress-strain correlations in frozen ground were favourably comparable within the small strain region. As the load was increased, however, the helical pile reached an adfreeze capacity of 1650 kPa followed by accelerated displacement. The smooth-shafted piles, in contrast, continued to withstand the applied loads because of their larger contact areas. The ultimate pile capacities were significantly decreased following ground thawing recording around 90% lower capacities. The load-carrying behavior of helical piles was dominated by their end bearing; therefore, it was important to drive the helical pile to a sufficient depth to ensure that the helix is located within the permanent frozen profile

Evaluation of candidate polymers to maximize the geotechnical performance of oil sands tailings

Oil sands fluid fine tailings deposits are challenging to reclaim due to their inherently high natural water content, low permeability, and low strength. Combinations of polymers and/or coagulants are used by operators to improve the dewatering and strength properties of the tailings. However, considerably more work has been done to evaluate polymer performance with short-term dewatering metrics rather than with long-term metrics such as consolidation properties. This paper evaluates the potential of four novel polymers for use in fluid fine tailings treatment compared to a commercially available polymer and untreated tailings specimen. The performance of the polymers was assessed through initial screening with respect to short-term dewatering, evaluation of the consolidation and strength properties using large strain consolidation tests, shear sensitivity in pipeline transport, and finally, large strain consolidation modelling to appraise the relative potential performance under different strategies, such as terrestrial or aquatic reclamation options. One polymer exhibits remarkably fast dewatering at high void ratios, while another demonstrates dense and shear-resistant flocs. The paper discusses each polymer's distinctive tailings fabrics and how their unique merits and limitations would benefit different reclamation eventualities. Finally, potential improvements of the polymers are suggested for future assessment.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author