Abstract:
Liquefaction mitigation of the native coarse and fine soils underlying a section of a tailings dam was identified as being necessary following a liquefaction assessment of the dam and its foundation. Based on the risk present if the ice-rich native course soils were to thaw and if the dam were to be subjected to a seismic event, it was determined that a ground improvement program was required in order to mitigate the risk of liquefaction of soils underlying the dam. The objective of the ground improvement was to improve the compressive and tensile strength as well as the elastic modulus of the foundation soils whilst maintaining a degree of drainage through the foundation. This paper will describe a field trial program involving the evaluation to two potentially suitable ground improvement methods identified to mitigate soil liquefaction in ice rich soils, in a remote arctic location, under challenging conditions. It will describe the application of the Cutter Soil Mixing and Jet Grouting methods at the project, and describe the geotechnical considerations and considerations relating to logistics, scheduling and risk. Furthermore, the challenges during the execution and main findings of the field trial program will be presented. Golder Associates were retained to provide proof of concept analysis, design, and subsequently, during the construction phase, quality assurance and quality control. Bauer Foundation Corp. was subcontracted to carry out the construction of the soil liquefaction mitigation field trial program using the two construction methods identified above as well as with the coring performed for quality assurance.