Application of Terrestrial Lidar and Photogrammetry to the As-Built Verification and Displacement Monitoring of a Segmental Retaining Wall

Terrestrial lidar and photogrammetry have significant potential for as-built verification and displacement monitoring of earth retaining structures. This paper focuses on application of a method for measuring the position of the wall facing to a tall segmental retaining wall (SRW) constructed in Conshohocken, Pennsylvania. The 3D point cloud data obtained using lidar or photogrammetry is processed by software developed in the Python programming language to produce vertical profiles of the wall alignment at user-specified locations. Profiles developed using point cloud data obtained at a single time are compared to the specified alignment and to measurements of alignment performed using a plumb line and total station. Profiles developed using point cloud data obtained at different times are compared to observe the displacement of the facing. Settlement of the wall is measured by comparing the position of horizontal block joints at different times.