The double-way and five-step ship lock was excavated through the ridge to the left of the hydropower complex, with upstream and downstream approach channels connecting to the Yangtze main channel. The total length is 6442 m including 1607 m for main body section. Continuous high slopes lie on both sides of the ship lock, with maximum height of 170 m, the area of more-than-120 m-high slope extends for about 460 m long.

Not only the overall and local stability of the side slope shall be ensured, but the creep of the side slope shall be strictly controlled to meet the normal operation requirement of the miter gate.

Considering the characteristics and the importance of the side slope, CTGPC took the following measures: drainage from inside the ridge, elimination of ground water, installation of pre-stressed steel-cords and high-strength steel anchors, and support with shotcreting. During the construction, CTGPC strictly followed construction procedure, applied a whole set of controlled blasting, strengthened prototype monitoring and feedback analysis, and carried out dynamic analysis. According to synthesis and analysis on the data collected from 3,268 monitoring devices embedded in every corner of the ship lock, the rock deformation became stable after excavation completed in April 1999. When the ship lock was put into operation, the shift in ship lock chamber is less than 0.5 mm during filling the lock chamber, fully meeting the normal operation requirement of miter gates.