การซ่อมแซมตอม่อสะพานที่ทรุดตัวด้วยเสาเข็มเจาะชนิดสปันไมโครไพล์

Abstract

This article demonstrates an approach to reinforce bridge’s foundations which had been settled from scouring with spun micro piles to substitute the existing piles. The bridge was built 27 years ago crossing Ranae Canal in Amphoe Phipun, Nakhon Si Thammarat. The Department of Rural Roads investigated the bridge in 2020 and found that two out of eight foundations settled down by 30 centimeters, causing the level of the bridge to no longer horizontal. This deflection significantly reduced the capacity of the bridge and would cause danger if it was still opened for traffic. The department examined a few solutions to the problem considering limitations on the construction space, necessity of traffic during the repairing process, cost, and safety for the construction, and then decided to reinforce the foundations with spun micro piles. The process began with driving the micro piles around the old foundations and constructing temporary structures to transfer the weight of the bridge to the new piles. The superstructure of the bridge was then lifted using hydraulic jacks against the load-transferring structures to obtain the desired level. Finally, new reinforced concrete foundations were cast on the micro piles to support the bridge. The result suggested the spun micro piles were able to support the weight of the bridge and complied with the design criteria and engineering standards.