Research on Refined Installation Management of Fully Dry-Connected Prefabricated Slab Based on BIM+3D Laser Scanning Technology

The fully dry-connected prefabricated slab completely avoids wet work on the construction site, which can make full use of the advantages of short construction period and environmental protection of the steel structures. However, due to the feature of completely prefabrication of the slab, it requires high installation accuracy. Existing BIM technologies cannot consider the production and assembly errors of prefabricated components. In order to solve the problem of increased costs such as time, transportation and manpower when return to the factory for remanufacturing caused by the failure of on-site assembly due to insufficient production accuracy of the fully dry-connected prefabricated slab, a refined installation management method based on BIM+3D laser scanning technology was proposed for the fully dry-connected prefabricated slab, which could complete precision detection and virtual assembly in the storage stage of prefabricated components, effectively avoiding cost waste caused by insufficient accuracy. The refined installation management method established a spatial coordinate system using a total station in precast component factory, and determined the position coordinates of each component in space through target points, and then used a three-dimensional laser scanner to scan the cover and base slab unit of the fully dry-connected prefabricated slab to obtain the point cloud data of each component. The advanced data post-processing software MAGNET Collage was applied to achieve target splicing, point cloud data fitting, point cloud segmentation and extraction, noise reduction and coordinate system establishment so as to obtain the point cloud model of each component and its spatial position, namely, the real scene replication of the component and its spatial position in the geometry sense was realized, and the digital twin model of each component of the fully dry connected prefabricated slab with production and assembly errors was obtained. Comparing and analyzing the digital model and the ideal BIM model created according to the drawings by docking and matching the spatial coordinate systems could obtain the size and position of the corresponding errors of the prefabricated components. The assembly errors of each component in the actual installation could be obtained through the virtual preassembly between the digital models of the cover and base slab units, adjusted the coordinates of the reference points to correct the errors and output the final coordinate adjustment data to guide the on-site installation of the corresponding components. Based on the above technologies, the construction quality and safety management method of the slab were proposed, which coordinates and manages the process from factory prefabrication to on-site assembly of the fully dry-connected prefabricated slab through the five stages of production, warehousing, pre-assembly, transportation and construction. The results showed that the refined installation management method can quickly obtain the digital twin model of the fully dryconnected prefabricated slab, and analyze its production accuracy, the maximum relative error is 5%, which meets the accuracy requirements; the assemble problems that may occur in site construction due to accumulated errors can be predicted through virtual preassembly, improving the on-site installation efficiency of the fully dry-connected prefabricated slabs in steel structures, effectively avoiding cost waste caused by insufficient accuracy. The refined installation management method based on BIM+ 3D laser scanning technology can be extended to other prefabricated structures with high accuracy requirements.