Abstract: On 5 July 2024, the embankment of Tuanzhouyuan of Dongting Lake in Huarong County of Hunan Province breached, eventually forming a major breach with a width of 226 m and an average depth of more than 10 m. China Anneng Construction Group Co. Ltd. was tasked to quickly take the lead in formulating the plan of breach sealing. They offered a technical solution of ‘immediate blocking along the axis of the original embankment with stone ballast closure dike’, and innovated the ‘two-way mechanized vertical blockage + shipment throwing on water’ rescue tactics, multi-material mixing dumping and shipment cluster blocking-on-water technology, and the design of composite anti-seepage and anti-wave system for the slopes on both sides of the stone ballast closure dike, integrated use of water, land and air three-dimensional measurement technology, monitoring technology and detection data assistance technology, solved the technical needs of rapid and efficient sealing of large-scale breach and the problem of anti-seepage of the stone ballast closure dike under the conditions of complex changes in the difference between the water level of both sides of the stone ballast closure dike. According to the procedure of ‘Quickly reinforce the head of the dike, two-way mechanized vertical blockage+throwing on water, filling the closure section of stone ballast closure dike quickly, reinforcing and heightening the dike, and preventing seepage’, finished filling the closure section of stone ballast closure dike 13.5 hours ahead of schedule, which is a classic example of timely and efficient sealing of large-scale embankment breach.