This job was a nice challenge from many points of views: Technical Diagnostic, Location and Remediation.
IGM was called to check the problem at this site when it was discovered that the abutment of Aboto Bridge had moved about 2m laterally and 0.3m settlement upon finishing the backfilling stage of the approach ramp. When the site was visited, the data about soil conditions, geometry and loading patterns were collected and analyzed. It was found that the abutment that was sitting on a group of piles had actually moved due to the lateral pressure due to the backfilling process. IGM suggested a solution that would consist of :
Removal of the Backfill sand material.
Installing Anchor cables in the bolting reservations of the mat /pile cap concrete formwork. Anchor cables would be anchored in a large dead man anchor block 100m behind the abutment wall and tensioned at the foundation level to pull back the entire abutment into place.
The approach ramp would be built as empty concrete boxes or cofferdams, laying on top of few piles. Some details of this solution are shown in the slideshow. The solution was implemented with great success!