The Terminal Port of Quebec intended to build a 48m diameter, 35m high grain silo located within Bécancour harbour (Qc). Menard Canada was awarded the soil improvement works to be completed under the silo, truck shelter and conveyor bases. Treatment was performed with an offset in order to ensure proper confinement for the structures and achievement of both settlement and bearing capacity criteria along with liquefaction resistance.
The proposed technique involved a combination dynamic replacement and dynamic compaction grid down to the dense sand/moraine through the existing fill. In order to avoid any damage to existing structures (some as close as 10m), vibration monitoring was used extensively and the height of compaction drops were locally adapted to ensure peak particle velocities of less than 50mm/s. Settlement and bearing capacity calculations based on 6 Pressuremeter Tests demonstrated achievement of the criteria. According to 3 SPT results, the soil is not liquefiable during an earthquake having a PGA of 0.314g and a magnitude of 6.5.