ABSTRACT
The overpass of Ch. 18.978 of the new highway Fier-Vlore in the West South of Albania less than one year after the opening to the traffic was closed due to excessive settlements of the abutments. This paper illustrates the work for analysing the causes of the problem and the design for the rehabilitation of the structure of the overpass. The abutments are constructed as an embankment of 8m on top of which was placed a RC raft with 4 piles 16m deep. From the geological re-study, it was seen that the geological layers, contrary to what was predicted, were a mixture of silty-clays and organic clays with very weak properties. To analyse the problem, consolidation analysis was carried out and for rehabilitation interventions of soil reinforcement by stone columns with vibro-compaction techniques and foundation reinforcement with additional piles were evaluated. Based on the detailed geotechnical analysis, it was estimated that the consolidation time for the soil-structure system was nearing its end. These analyses were verified by the monitoring in site and was decided for an intervention only to reposition the superstructure of the overpass and the replacement of the damaged supports and bearings. The article indicate the importance of a pre-consolidation process, the proper calculation of time of consolidation and monitoring influence to the performance of the overpass structure.
