Keywords: geotextile, geosynthetic, geotube, finite element, slope stability, retaining wall, soil plasticity, ABAQUS.

Slope stabilization is traditionally achieved by a wide variety of internal and external approaches. Creating soil retention structures such as reinforced concrete or modular retaining walls are some of the methods for external stabilization. Structures such as these require design and construction expertise. In an effort to develop a soil retention structure that can be constructed cheaply, quickly, and by untrained workers, a design composed of stacked geotextile tubes is investigated. The only crucial construction material required for a structure of this nature is the geotextile. The tubes can potentially be filled with on site soil. In the construction of this type of structure, some experience will certainly improve the results, however, the need for skilled labour will be minimal. This allows stacked geotube soil retention structures to be implemented virtually anywhere in a cheap and timely fashion. Work pertaining to design techniques and structure performance is required.

This paper presents a three dimensional finite element model of stacked geotextile tubes to be used as a soil retention structure. The model consists of an embankment defined as a large block of soil extending beneath and in each direction from an unstable slope. Lining the face of the slope is a stack of three geotextile tubes, each approximately 1.5m high.

This model is created for two purposes. The main objective is to develop the necessary techniques for modelling any geotube structure. These techniques involve obtaining the correct geometry of each tube, defining realistic material constitutive models, defining realistic interactions between different regions of the model, and having the ability to easily implement innovative design modifications and observe their effects. Also, an effective approach for interpreting results is needed. All of these were achieved and details pertaining to each are presented in this paper.

Another objective of this model is to test the three tube stack design as a retaining structure for stabilizing the slope. Two slopes are considered, 45 degrees and 55 degrees. Each of these slope angles is intended to be unstable. In addition, for each slope a surcharge varying in proximity to the embankment edge was applied. Results between models without the tubes in place and with the tubes in place were compared.

Based on displacement and plastic strain figures, it is observed that when the tube stack is implemented, the lateral displacements in the unstable slopes are reduced by between 50 and 60 percent.

The model considered here and the techniques used to create it can be used as a basis for creating models of any stacked geotextile structure. The particular design tested here appears to be effective in stabilization of a slope with a surcharge load by means of reducing displacements. Future model improvements will include improving constitutive material models used, improving interaction behaviour, and developing a failure criteria based on the factor of safety obtained.

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