Realistic results with new design model for piled embankments

Published: 1 July 2015

A new design model for piled embankments produces results that almost perfectly match the actual situation thanks to the doctorate research conducted by Suzanne van Eekelen, a geo-engineering expert with Deltares. Suzanne's study has produced a model that predicts the behaviour of piled embankments with geosynthetic reinforcement much better than the current models.

Piled embankments are used as the foundations for roads or railways on soft subsoil. They consist of a foundation of piles below a bed with geosynthetic reinforcement. Suzanne’s new model reduces the uncertainty in the calculation of the strains in the geosynthetic reinforcement by a factor of 2.5. This makes piled embankments a fully viable alternative for roads and railways on soft subsoil.
Designers can use the model to produce economic and safe designs for piled embankments. Management agencies will be able to make budgets for maintenance work on embankments more precise and to manage road quality better. An entirely new CUR guideline for piles embankments will be produced after the summer using Suzanne’s new design model. There is also considerable international interest in the study and the model, for example from America, China, Asia, Brazil, Germany, Poland, Mexico, Korea, Indonesia, France, Finland, Sweden and China.

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The new piled embankment model (Concentric Arches). The loads are transported along the hemispheres and the 2D arches, towards the piles, the geosynthetic reinforcement and the subsoil.

 

Calculated and measured results match perfectly

A series of experiments were conducted for the study in the Deltares Geolaboratory. Suzanne used the results to develop a new design model. She compared the results of the model with field measurements from seven actual projects and three other series of experiments. Suzanne van Eekelen: ‘We now understand much better how piled embankments work. And we can give exact predictions of how the embankments will behave and produce precise designs. We have reduced the margin of error in the model and so there is less risk of any unexpected events. That is the major benefit.’

Piled embankments suitable for use in areas susceptible to land subsidence

Piled embankments have been used in the Netherlands since the beginning of this century. There are at least 60 at present. More and more roads of all kinds are being built on piled embankments, which are particularly useful as foundations in areas with soft subsurfaces where land subsidence is a feature. Once they have been built, residual settlement is minor or non-existent and that makes piled embankments virtually maintenance-free. The technology can also be used when pre-loading is not possible, either because there is no time or because there are vulnerable networks, buildings or existing roads in the immediate vicinity. The embankments require almost no maintenance and they can be built quickly.

Study receives international awards

Together with her colleagues Adam Bezuijen and Frits van Tol, Suzanne van Eekelen has received several awards for the work on her doctorate study in recent years. The last one was the IGS Award, the most prestigious award granted by the IGS. It is handed out once every four years to people or groups who have completed research that makes an exceptional contribution to the development and use of geosynthetics.