Construction and Post-Construction Deformations of an MSE Wall using Terrestrial Laser Scanning

Devon Adamson, Marolo Alfaro, James Blatz

In the proceedings of: GeoSt. John's 2019: 72nd Canadian Geotechnical Conference

Session: Transportation Geotechnics

ABSTRACT: Terrestrial Laser Scanning (TLS) is a surveying tool that can create a 3D point cloud by shooting a web/mesh of laser points in different station locations in a 360° range of its surroundings. These scans can be registered to align itself from like surfaces, points, or objects and can be accompanied with pictures to create context and colour to the surfaces. The use of this technology can range from measuring dimensions of existing structure conditions for renovations, deformation monitoring of natural slopes, and risk management for rockslides on mountain sides. A laser scanner was used to measure settlements from the Mechanically-Stabilized Earth (MSE) wall abutments. The results were compared with the readings from a total station to determine its reliability and compatibility for applications in civil construction applications.

RÉSUMÉ: Le balayage laser terrestre (TLS) est un outil de mesure permettant de créer un nuage de points en 3D en réalisant une toile / un maillage de points laser dans différents emplacements de station sur une plage de 360 ° de son environnement. Ces numérisations peuvent être enregistrées pour s'aligner sur des surfaces, des points ou des objets similaires et peuvent être accompagnées d'images pour créer un contexte et une couleur pour les surfaces. L'utilisation de cette technologie peut aller de la mesure des dimensions des conditions de structure existantes pour les rénovations au suivi de la déformation des pentes naturelles, en passant par la gestion des risques pour les éboulements rocheux sur les flancs des montagnes. Un scanner laser a été utilisé pour mesurer les colonies à partir des culées murales en Terre stabilisée mécaniquement (MSE). Les résultats ont été comparés aux lectures d'une station totale afin de déterminer sa fiabilité et sa compatibilité pour des applications dans les applications de construction civile. 1 PROJECT BACKGROUND The McOrmond-College drive bridge interchange in Saskatoon is a project that began construction in April 2018. The interchange was first proposed in order to help alleviate heavy traffic as the commuter population in that area has grown steadily over the years, causing more fuel consumption from the increased traffic delays (City of Saskatoon, 2017). The bridge interchange has 2 lanes of traffic for the 80km/h speed limit College drive roadway and 2 lanes for Northbound McOrmond drive and one lane for Southbound at 60km/h. The bridge has 3 lanes over the existing College drive. The bridge structure is supported by a total of 21 Cast-In-Place (CIP) belled piles. Approach fills for the bridge are approximately 8 to 9 m high and have an MSE wall face running parallel to College Drive. The approach fills are supported by a total of 240 vibration-compacted stone columns (120 each at the North and South Abutments). The maximum estimated settlements for this structure is up to 55mm. The settlements were measured during construction through a combination of settlement plates and surveying of the MSE wall face. A study has been undertaken to determine if Terrestrial Laser Scanning (TLS) can provide a reliable and applicable surveying technique to measure movements in the MSE wall. Figure 1 Existing roadway conditions

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