PENTA-OCEAN CONSTRUCTION CO., LTD. We conducted a field demonstration test of this technology on a 24m section of waterproofing work in the 'Sasebo Road Yumihari Tunnel Construction (Ordering party: NEXCO West Japan Kyushu Branch)' and confirmed that it can contribute to labor saving and safety improvement.
Traditionally, waterproof sheets are welded in mountain tunnel construction by three workers handing welding machines around the circumference of the tunnel. It was one of the toughest jobs in high places because the welding machine was operated by hand in a narrow space on a scaffolding cart. The installation of the waterproof sheet required a 3-dimensional slack to match the unevenness of the shotcrete finish on the back, so welding the sheet required the work of a skilled worker.
This system automatically welds the waterproof sheet while the welding machine on the guide rail attached to the scaffolding truck moves. The seesaw, slide, and rotation structure and balancer built into the main body of the automatic welding unit allow the welding machine to move forward, backward, left, right, up and down while maintaining balance along the twists and deflections of the welding line, achieving automatic welding. In addition, since the welding machine can be moved at a constant speed according to the welding speed, we were able to ensure the quality of the welded part. Furthermore, by attaching a sheet fixing jig to the top of the welding roller, it is possible to prevent the sheet from being taken into the welding roller with wrinkles remaining.
At the demonstration site, one worker was assigned as a supervisor to perform on-site verification, and it was confirmed that automatic welding could be performed over the entire welding line. We have achieved a reduction in the number of welding workers (skilled workers) in the scaffolding and liberation from hard work. Visual and pressure tests confirmed that the required time was the same as before, and that the quality of the welded part was ensured.
In the future, we will implement the introduction to each site. We aim to improve the productivity and safety of waterproofing work, which is one of the construction cycles of mountain tunnel construction, by expanding the scope of automation, such as sheet stretching and quality control of welded parts, and improving the welding speed.
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