Boring 1000m in Sand Formation without Flatspotting

In a jobsite of Guangzhou Metro construction, the ground was sand formation and it’s very soft, but there were some boulders in it. So scrapers were not fit to be utilized because the scrapers would be easily destroyed by the boulders. The contractor who once used our TCI disc cutters previously once again adopted our TCI disc cutters. This time, they used our TCI disc cutters in order to bore a longer distance and to prevent the problem of flatspotting.
In fact, their choice was correct. After boring 1000m, our TCI disc cutters were still in good shape and no problem of flatspotting at all. The following is the pictures taken from the jobsite.