**Abstract:** The multi-section floating box gate is an innovative inspection gate that combines the advantages of conventional and floating gates, without the need for permanent opening and closing mechanisms. Designed to address specific project requirements, it ensures stable positioning and minimal water flow disturbance. This type of gate is cost-effective, easy to operate, reliable, and requires minimal maintenance, making it a highly economical solution. Key words: Multi-section design, floating gate, maintenance gate, energy dissipation, structural optimization. **1. Introduction to the Multi-Section Floating Box Gate** The multi-section floating box gate integrates the benefits of traditional stacked beam gates and floating gates, tailored to meet the unique conditions of the Xiaolangdi Project. It is specifically designed for the 1# orifice discharge spout, where three flood spillways are arranged with two entrances each, including maintenance and accident gates. The central chamber divides the flow into two channels before merging them downstream. Due to the high flow velocity through the orifice, frequent inspections are necessary. The gate is positioned in a submerged tunnel, requiring a temporary inspection gate at the exit to isolate the chamber during maintenance. During the preliminary design phase, the layout of conventional flat gates was considered, but the high-speed water flow caused cavitation damage, making them unsuitable. Floating gates were chosen due to their lower cost and ease of operation. The gate’s structure allows it to float above the water, eliminating the need for complex underwater equipment. Its multi-section design enables efficient transport and storage in the suspended pond, avoiding sedimentation issues in the power pond. **2. Advantages of the Multi-Section Floating Box Gate** Compared to other inspection gates, the multi-section floating box gate offers several key benefits: (1) All operations are conducted above water, ensuring safety and reliability; (2) Equipment can be fully removed after maintenance, reducing long-term wear; (3) No divers are required, saving labor costs; (4) No underwater hook systems are needed, simplifying the structure; (5) Reduced lifting capacity lowers equipment costs; (6) The box-shaped structure provides greater rigidity and mechanical performance, especially for large openings. **3. Design and Construction Details** The gate is composed of multiple sealed sections, each with a cavity that allows it to float. The overall dimensions are 12 meters wide, with a design head of 9 meters. The structure includes upper and lower cabins connected by bulkheads, enabling smooth floating and transportation. Each section has air and drainage valves, along with manual ball valves for control. A ladder is installed for valve access, and lifting lugs are used for positioning and hoisting. Support blocks and positioning pads are made from low-density engineering plastics, ensuring stability and durability. Sealing is achieved using P-type rubber gaskets, forming a continuous U-shaped seal between sections. The embedded system includes guide slots and support structures, allowing the gate to smoothly enter and exit the slot. The draft depth is less than 1 meter, facilitating easy movement. **4. Operation and Maintenance Process** The gate is transported using a car crane, floated into place, and secured with ropes and manual hoists. Air compressors are used to inflate the chambers, allowing controlled submersion. After maintenance, the gate is deflated and retrieved using the same process. The entire operation is simple, safe, and cost-effective, minimizing downtime and equipment costs. **5. Conclusion** The Xiaolangdi multi-section floating box gate successfully completed its first maintenance task in 2001, proving the effectiveness of the design. It operates reliably under high-flow conditions, avoids the need for complex underwater infrastructure, and significantly reduces long-term maintenance efforts. This innovative gate type is ideal for similar projects, offering a practical and economical solution for maintenance and inspection in challenging environments.

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