Diaphragm wall displacement due to creep of soft clay

The analysis and design of diaphragm wall displacement due to creep of soft clay have traditionally been ignored, probably because of ignorance of its significance, or of the need for complicated finite-element analysis. Using data retrieved from a soft clay excavation site in Taipei city supported by a diaphragm wall, a finite-element study using the soft soil creep model has been employed to back-analyse the instrumented data and calibrate the appropriate use of the model, its material parameters and the modelling process. The soft soil creep model and the material parameters were used in a series of parametric studies to evaluate the relation between support stiffness and wall displacement due to undrained soil creep, and the associated creep rate of the wall. Simple equations were obtained in terms of the maximum excavation depth and support stiffness, which is a function of the support spacing and the flexural stiffness of the wall. The results of this study provide valuable reference information for future design of diaphragm walls in similar ground conditions.