Shen w blocks Garen ult, is this intended?

Played against a Shen as Garen today, when I tried to tower dive him lvl 10 with him at around 400 health, I ulted him in his w but he barely lost any health. Since he was not the villain at the time and was relatively fed and tanky, I thought it maybe due to his shield and merc treads and so on. However, later in a teamfight I used lvl 2 ult on the Lee Sin at low health, again in Shen's w, and no damage was done. Wondering if it is intended for Shen's w to block Garen ult on top of basic attacks? Does Garen ult count as a basic attack then? (lol)