Application of Terrestrial Laser Scanning for the Displacement Monitoring of GRS-IBS Abutments

Bridge abutments constructed using geosynthetic-reinforced soil (GRS) with an integrated bridge system (IBS) are becoming increasingly popular because of cost efficiency and rapid construction. Monitoring the vertical and lateral deformations of the GRS-IBS facing is one technique that has been used to assess performance. The conventional approach is to measure vertical and lateral deformations using a standard survey level and rod. This paper describes lessons learned from the use of three-dimensional (3D) stationary terrestrial laser scanning (TLS) to measure facing displacements for a two lane 32 m long GRS-IBS constructed in Sheffield, MA. The intent was to measure displacement of the split-face segmental concrete block facing by comparing position measurements obtained before and after placement of the bridge deck on the abutments. A simple procedure is followed to analyze the point clouds. The high measurement density and resolution provided by the laser scanner enables detailed observation of how the abutments deform in response to the applied loads. The capability of the proposed procedure to measure displacement is discussed in the context of the displacements allowed in the current GRS-IBS design methodology.