Analysis of a Diaphragm Wall Panel After Leakage During Deep Excavation

Instances of leakage from the joints between the panels of a diaphragm wall, during construction, are not uncommon and several cases have been reported in literature, along with measures taken for repair and rectification. This paper deals with one such case wherein, following repairs to stop the leakage, a parametric study was carried out using PLAXIS, considering various scenarios of subsoil disturbance, both the decrease in the subsoil strength as well as likely extent of zone of disturbance. The back-analysis was based on the data from the inclinometers, installed in the diaphragm wall panels and cone penetration tests carried out to establish the subsoil condition, pre and post leakage. This enabled to establish the most probable combination for assessment of the BM developed in the wall for ascertaining its structural adequacy. Based on the study it was concluded that the disturbed zone is limited to about 5 m beyond the face of the D’Wall, defined by Case A. The computed deformation for the lower Es values (Cases B and C) and 10 m disturbed zone (Case D), is much in excess of the observed deformation, hence not applicable.