A gravity dam at a major hydroelectric complex underwent its first systematic underwater inspection after 15 years of operation. Facing challenging conditions with underwater visibility less than 1 meter and strong turbulent currents in multiple areas, an underwater robot successfully completed the task.
During the two-day operation, the underwater robot demonstrated multiple advantages that traditional manual inspections struggle to match:
All-Weather Operation Capability was the primary highlight of this inspection. The robot is unaffected by lighting conditions, functioning effectively at night and in turbid water. While inspecting the flood discharge channels, the robot maintained stable positioning against currents reaching 2.5 m/s using its vector propulsion system—conditions that would pose significant safety risks for human divers.
Precise Data Collection represents the core value of robotic inspection. At a depth of 25 meters, the robot detected a concrete surface defect. It not only recorded high-definition imagery but also used its robotic arm-mounted thickness gauge to accurately measure a 12% reduction in concrete thickness. Notably, while traversing the dam's expansion joints, the robot identified three sealing strip damages at millimeter scale, with sensors accurately detecting minor seepage at one location. This precise data provides reliable foundations for subsequent repairs.
Intelligent Operation Mode significantly improved inspection efficiency. The robot automatically optimized its inspection route based on the dam's structural characteristics. When anomalies were detected, the system increased scanning density from the standard 50 cm intervals to 10 cm intervals, ensuring no detail was missed. The entire inspection was completed in just 8 hours—work that would typically require 20 hours using traditional diving methods.
Comprehensive Cost Advantage was equally significant. This robotic inspection reduced direct costs by approximately 45% compared to traditional diving inspections. More importantly, the robot operation required no large-scale safety protection systems and was unaffected by weather windows, saving substantial indirect costs and time for the reservoir management department.
Digital Results Output laid the foundation for long-term management. The 3D point cloud model and digital inspection report generated by the robot created an accurate "digital file" of the dam's underwater condition. All defects were documented with precise coordinates and detailed measurements, enabling management to develop scientific maintenance plans and make accurate comparisons during subsequent inspections.
Most notably, while completing routine inspection tasks, the underwater robot accessed multiple "hard-to-reach areas" that are challenging for traditional diving inspections—including deep sections of flood discharge channels and structural connection points—achieving truly comprehensive inspection coverage.
As underwater robot technology matures, dam safety management is transitioning from reliance on human experience to data-driven approaches. This transformation not only enhances inspection safety and accuracy but, more importantly, provides reliable technical foundations for preventive maintenance and lifespan prediction of hydraulic facilities. This inspection case validates that China's hydraulic facility maintenance has entered a new stage of intelligent, digital management.