A Generalized Newmark Method with displacement hardening for the prediction of seismically-induced permanent deformations of diaphragm walls

The paper presents a Generalized Newmark Method incorporating a displacement hardening mechanism for the prediction of permanent displacements accumulated by diaphragm walls during earthquakes. A key feature of the proposed approach is the adoption of an evolution law for the critical acceleration, which links its current value to the accumulated wall permanent displacements. This displacement hardening mechanism is based on a simplified relation between the average plastic shear deformations experienced by the passive zone of soil below dredge level and the mobilized soil friction angle. This relation is determined indirectly by the evolution of the passive earthpressure coefficient with wall displacement/rotation, as obtained in quasi-static model wall experiments. The proposed approach has been validated by comparing its predictions with the experimental data obtained in centrifuge model tests of cantileveredand propped walls. In spite of the simplifying assumptions on which it is based, the GNM has demonstrated capable of capturing the essential features of the retaining structures kinematics and provides realistic predictions of permanent wall displacements.