lateral pile group

6.12 Laterally loaded pile group

Behavior of laterally loaded pile groups

Fig. 1 Deformation pattern of both pile and ground, DPRI, Kyoto Univ., Japan

Fig. 2 Horizontal loading test of inclined pile, DPRI

Fig. 3 Side view of damaged piles, DPRI

Fig. 4 Side view of damaged piles, DPRI

Fig. 5 Reinforcement steel bars for concrete pile model, made with piano wires, DPRI

References

Geotechnical Engineering Group of Kyoto University (1994) : Technical Digest of Geo-Centrifuge Studies, No. 1, DPRI, Kyoto Univ.

Kimura, M. et al. (1997) : Ultimate behavior of axially-loaded steel piles subjected to cyclic lateral load, Proc. of Int. Conf. on Foundation Failure, pp. 405-415.

Kimura, M. and Adachi, T. (1997) : Failure mechanism of laterally loaded concrete piles by centrifugal model tests, Proc. of the Int. Conf. on Foundation Failure, pp. 417-426.

Adachi, T., Kimura, M., Morimoto, A. and Kobayashi, H. (1994) : Behavior of laterally loaded pile groups in dense sand, Proc. of CENTRIFUGE 94, pp. 509-514.

Lateral loading of pile groups due to embankment construction

Construction of embankments on soft clay results in time dependent embankment settlement, and both vertical and horizontal movements within the clay. Where the embankment forms an approach to a piled bridge abutment, it is often necessary to install the abutment piles before full deformation of the embankment has occurred. The piles may therefore experience significant lateral loads from horizontal soil movements, as illustrated in Fig. 1.

A series of experiments was performed at The University of Western Australia as described by Stewart et al. (1994a), to examine the response of piled bridge abutments to lateral loading induced by embankment construction. Models with different soil strength, stratigraphic profiles and differing pile group layouts were tested.

The modelling procedure involved:

pre-installation of a pile group instrumented to record pile bending moments and pile cap deflection;
consolidation of the sample at 110 g;
in-flight construction of a sand embankment in a number of lifts using a hydraulically operated sand hopper;
monitoring of pile instrumentation, embankment settlement and pore pressures in the soft clay over an extended period.

The results of these experiments helped to clarify the behaviour of piled bridge abutments on soft clay and were used to derive empirical design charts as well as provide good reference data for comparison with analytical methods and design techniques (Stewart et al., 1994b).

Fig. 1 Pile group adjacent to an embankment, University of Western Australia, Australia

References

Stewart, D.P., Jewell, R.J. and Randolph, M.F. (1994a) : Centrifuge modelling of piled bridge abutments on soft ground, Soils and Foundations, Vol. 34, No. 1, pp. 41-51.

Stewart, D.P., Jewell, R.J. and Randolph, M.F. (1994b) : Design of piled bridge abutments on soft clay for loading from lateral soil movements, Geotechnique, Vol. 44, No. 2, pp. 277-296.