Embankment supported on piles with biaxial geogrids

Abstract

The case study consists of a piled embankment built over a very soft, organic compressible clay layer 10 m deep. The height of the embankment supported on piles was about 1·3 m, and the piles, which measured 0·18 m × 0·18 m, were spaced 2·5 m apart in a square pattern, with 0·8 m wide square pile caps covered with a bidirectional 200 kN/m geogrid polyester reinforcement. A region of the piled supported embankment was instrumented to provide a better understanding of the overall embankment-reinforcement-pile cap system. Three-dimensional and two-dimensional pile layouts were adopted. An excavation of 1 m under the geogrid was carried out to induce rapid load transference to the geogrid. The settlement in between pile caps was 0·10–0·4 m, whereas settlements in the region under similar embankment heights were much higher, thus demonstrating the efficacy of pile-supported embankments with geogrids in controlling settlements. Strains at the reinforcement were also measured, and showed values in the range 0·25–2·05%.

Design Guideline Basal Reinforced Piled Embankments

“…GR strain gauges ( in Figure 5.4) consisted of an ingenious system described by Almeida et al (2007) which measured the strain using strain gauges on a steel bar that had been attached with a reaction spring to the GR. …”

“…Seven full-scale cases have been reported with the data that will be considered in the present paper: in Brazil (Spotti, 2006;andAlmeida et al, 2007 and2008), in Houten, the Netherlands , near Woerden, the Netherlands ( , in Finland (Huang et al, 2009, including FDM calculations), in the Krimpenerwaard, the Netherlands (Haring et al, 2008), in Hamburg, Germany (Weirauch et al, 2013) and in France (Briançon and Simon, 2012). Additionally, four series of model experiments reported in the literature are considered in the present paper: from Virginia (Sloan, 2011 andMcGuire et al, 2012), the Republic of Korea (Oh and Shin, 2007), Germany (Zaeske, 2001, also reported in Kempfert et al, 2004) and the Netherlands (Van Eekelen et al, 2012a and b, adopted in Chapter 2 and 3 of this thesis).…”

“…Furthermore, the authors of the present paper believe that the available data for the working condition are sufficient to determine the reliability of the analytical models for the working condition. Almeida et al (2007Almeida et al ( , 2008) present measurements in a full-scale experiment carried out in the Barra da Tijuca District of Rio de Janeiro. The project has also been described in Spotti (2006), McGuire et al (2009), and Zhuang et al (2014).…”

Renforcement d’un remblai par inclusions rigides : approche expérimentale

“…Une analyse plus complète, avec une modélisation numérique des nappes, permettra de vérifier si la différence de transfert de charge observée peut être expliquée par la nature des géosynthétiques. Peu d'expérimentations en vraie grandeur permettent une analyse pertinente de ces mécanismes ; on citera cependant celles d 'Almeida et al (2007) ou Liu et al (2007) qui amènent à des observations semblables aux nôtres, en particulier sur : -l'influence de la réaction du sol compressible sur le tassement différentiel notamment lorsque la couche superficielle est de bonne qualité (Almeida et al, 2007) ; -le transfert de charge vers les inclusions rigides via une plate-forme granulaire renforcée et la répartition des tensions dans les nappes géosynthétiques (Liu et al, 2007).…”

Editorial

“…Results show that the existing methods generally lead to a conservative design; however, comparison between different approaches is recommended to optimise the design. Another case study of instrumented geogrid-reinforced and pile-supported embankment was presented in this journal by Almeida et al (2007); however, in that case the foundation soil consisted of highly compressible organic clay. Tarawneh et al (2018) propose a review of different traditional methods to predict settlements, by elaborating upon data collected by means of shallow foundation load tests on desert sand in Oman.…”