CASE STUDY
Quay Reinforcement with Rigid Inclusions – Port of Le Havre
Date:
2021
Industry Area:
Civil
Client:
EGIS – NGE Fondations
ITASCA Office:
France
FLAC3D
Project Background
As part of the reinforcement work of the Joannes Couvert quay in the Port of Le Havre, soil reinforcement by rigid inclusions (RI) is planned in the rear of the future quay structure to allow the passage of heavy cranes during the operational phase. The reinforcement solution consists of rigid inclusions 300 mm in diameter with a square mesh of 1.5 m per side, for a total of approximately 3,400 inclusions of about 20 meters in length over the entire area.
The reinforced zone also includes a 2.5 m thick surface load transfer platform (PTC) made of granular material and reinforced with three layers of geogrid.
With the level of stress exerted under the crane caterpillars being much higher than the usual levels considered in soil reinforcement projects, numerical modeling with FLAC3D is necessary to better understand and evaluate the load transfer mechanisms in the PTC and, finally, to estimate the associated settlements.
ITASCA’s Role
The FLAC3D model includes a complete crawler crane, the PTC reinforced with geogrids, and a foundation given by a multilayer soil reinforced with a network of 200 RI.
The crawler is represented by a rigid plate with a trapezoidal load varying from 290 to 790 kPa between its front and the back ends.
Geogrids are modeled by a network of intersecting cable structural elements, while IRs are modeled by pile elements and include a shell plate with a surface area equivalent to their section, at the level of the inclusion head and base, to ensure correct transfer of the vertical loads between the soil and the inclusions.
Featured ITASCA Software
FLAC3D
Project Results
The calibrated 3D numerical model validates the proposed reinforcement solution with RIs with respect to the differential settlement of the caterpillar (< 3 cm), even when considering a conservative hypothesis for the soil moduli. The settlement at the level of the caterpillar is much higher (x3) than that at the inclusion head, indicating the presence of a PTC punching mechanism, with limited load distribution in the granular material. The calculation of the internal forces in the inclusions (MNT) induced by the localized loading has also made it possible to justify a concrete section. The model shows a marginal contribution of the geogrids to the reduction of settlements and forces in the RIs.
