When there are only 6 to 10 steel sheet piles left in the cofferdam, consider the closing process and measure the actual width of the closing opening. If the closing opening width matches the effective width of the remaining sheet piles and the locking ends are parallel, the remaining sheet piles can be inserted sequentially and then driven into position. If the locking ends are not parallel and the distance between the ends is within a certain range, the following measures can be taken to adjust the situation:

1. If the upper ends of the steel sheet piles are tilted toward the closing opening, use a jack to push the top ends of the steel sheet piles together or use two sets of fall chains to tension them outward to the desired spacing.

2. When inserting the closing sheet piles, external force may be required to lower the closing sheet piles because the adjusted spacing is not completely parallel. Alternatively, if there is still a significant length of steel sheet pile that does not fit into the locking ends and hammering is not feasible, a fall chain can be installed at the top and the lower end of the fall chain secured to pull the steel sheet piles into the locking ends.

When the steel sheet piles cannot be closed due to other reasons after taking the above measures, special-shaped steel sheet piles can be made to close them. Special-shaped piles are generally made into wedges, with one end larger than the other end. The slope of each wedge pile does not exceed 2%. If one wedge pile is still not enough to close the mouth, two wedge piles can be used. Each wedge pile has a vertical edge, and at least one ordinary pile is inserted in between.