Numerical modeling of dredged sand filled geotextile tubes behavior under seismic loading

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Client Name 
Geosintex S.R.L.
Software Used 
Project Description 

A nearshore 120m long causeway is planned for the Mozambique LNG TMOF Project. Geosintex S.R.L. proposes a structure composed by synthetic geotubes (see Figure) for protecting the road against erosion.

The mechanical behavior of this structure must be understood better. The evaluation of the potential for liquefaction of the road sandy basement and the geotubes filling material is of
particular interest.

Itasca's Role 

Itasca Consultants SAS built and ran a numerical model using the FLAC software to analyze the stability of simple structures including dredged sand‐filled geotubes, including an evaluation of their liquefaction potential. This preliminary analysis helped verify the capability of FLAC to allow an advanced stress deformation analysis that includes the direct assessment of the liquefaction potential for the geotechnical structure.

The FLAC implementation of the PM4Sand model (see references) was adopted at this scope.

Project Results 

The model has shown the capability of addressing the liquefaction risk for geotechnical structures composed by geotextile tubes filled by dredged sand.

The stability of such structures, for the conditions that were tested, doesn’t seem to be greatly affected by susceptibility to liquefaction. Strength properties of the interfaces between the tubes and the base rather seem to be more critical.

Project Image(s) 

Itasca Consulting Group, Inc. (2011), FLAC (Fast Lagrangian Analysis of Continua) user's manuals, Minneapolis, MN

Boulanger, R. W. (2010). A sand plasticity model for earthquake engineering applications Report No. UCD/CGM‐10‐01, Center for Geotechnical Modeling, Department of Civil and Environmental Engineering, University of California, Davis, CA,77 pp