Centrifuge Modelling of Diaphragm Wall Construction Adjacent to Piled Foundations

Abstract

Abstract Diaphragm walls are often implemented to support the sides of deep excavations and in urban environments situations increasingly occur where it is necessary to install them close to existing piled structures. There is a lack of good quality field monitoring case studies to help understand this complex three-dimensional soil–structure interaction problem. It can be investigated using numerical analysis or an alternative approach is to perform small-scale model tests in a geotechnical centrifuge. This paper describes a sophisticated model construction system that was developed to simulate the construction sequence (excavation and casting of concrete) of a single or series of three diaphragm wall panels in sand as part of a study to investigate the influence of constructing diaphragm walls adjacent to piled foundations. Prior to wall construction an adjacent instrumented model pile was driven in-flight and a constant force maintained at the pile head to simulate axially loaded piles. The system response was captured through the use of miniature soil stress cells, LVDTs, and laser displacement sensors. A detailed description of the centrifuge model and test procedures developed is presented and the necessary simplifications and associated errors discussed. The effectiveness of the small-scale physical model is demonstrated by presenting some selected test results (soil stresses and deformations).