Menard offered to Winvic a solution of Dynamic Replacement (DR) in alternative to the base solutions consisting of the remediation of the made ground with clearance of the obstructions and soft pockets ahead of the use of Vibro Stone Columns. The use of DR allowed the ground improvement works to be undertaken without the need for a prior remediation.
Menard designed the Dynamic Replacement to reduce the residual settlements under the exploitation loads to 25 mm with relative differential settlements limited to 1/500. The installation of the DR allowed to increase the bearing capacity beneath the footings to 200 kPa SLS. The final design comprised 1,253 DR pillars of diameter between 1.4 and 2m to 2.5 to 6m depth.
The DR have been installed over a period of 12 weeks, with 1 rig. The works have been verified through a thorough quality control, comprising post-DR CPTs, dummy foundation tests and a long duration zone load test.
The use of Dynamic Replacement allowed to get rid of the need for remediation of the made ground ahead of the ground improvement works which lead in no contaminated material being sent off site, therefore saving on the site overall embodied carbon footprint.