3D finite element analysis of deep excavations with cross-walls

Ground movements induced by deep open excavations retained by diaphragm walls may be substantially reduced using sacrificial cross-walls installed as props between the retaining walls. In this paper, a 3D finite element study is presented in which the retaining walls and the cross-walls are modelled using brick elements and accounting for the interfaces between the panels of diaphragm walls and of cross-walls. Influence of cross-walls spacing and length in reducing the horizontal deflection of diaphragm walls and the ground settlements behind the excavation is evaluated. Companion plane strain analyses, in which an homogeneous equivalent medium is considered in between the retaining walls, are also presented to assess the capability of 2D analyses to predict the performance of deep excavations in which cross-walls are used as a mitigation measure to reduce wall deflections and ground movements.