Forensic Analysis of Retaining Wall Failure: Fid-Bau Portal

Forensic Analysis of Retaining Wall Failure

Aravind, P. S. / Mohan, Neerad

The cause of the failure of the gravity wall in Chalakudy, Trichur district of Kerala state, India, is determined by forensic geotechnical engineering. The wall is located along the Chalakudy river and nearby the railway track thus subjected to train-induced ground vibrations. The vibrations produce resonance conditions in the soil which is responsible for liquefaction. As a result, the soil loses its bearing capacity and undergoes settlement. The dynamic active earth pressure induced by vibration along with hydrodynamic loads due to the river induces additional lateral thrust on the wall. Hence, the ground vibration induced by the train acts as a ‘trigger’ which causes premature failure of the wall already weakened by other causes like liquefaction, settlement, and earth pressure. The ground vibration parameters are measured by triaxial accelerometers ADXL 335. Displacement and settlement calculations of the wall which showed distress in the form of translation and vertical settlements are presented. Further, back analysis of gravity retaining wall is performed using conventional methods and FEM software PLAXIS 3D. Back analysis of failure showed that the mechanism of failure is predominantly due to bearing capacity failure and the deformations are in conformity with the predictions obtained from numerical analysis and actual site conditions. From the results of the back analysis, it is observed that the retaining wall designs based on prescriptive guidelines may not lead to satisfactory designs, and considerations of deformations, selection of the backfill material, properties of the foundation soil, better foundation design, etc. are important for maintaining the structural integrity of the wall.