Discussion

SESSION 2

C.W.W. NG, University of Bristol Recently, I have been involved in the back-analysis of the 10 m deep multipropped underground carpark constructed top-down in Gault clay at Lion Yard Cambridge.1 The site was unusual in that there was the opportunity to monitor both the wall deflections and the strut loads, as well as pore pressures, ground movements and total stresses on the face of the diaphragm wall which allows a comparison between the observations and retrospective predictions. A cross-section of the site is shown in Fig. 1.

The back-analysis was carried out using the non-linear finite element Brick model,2 which has the capacity to mimic the soil behaviour at small strains. Careful thought was given to modelling the wall installation, and it is believed that the non-linear soil behaviour is very significant at this stage of the analysis.