Beneath the very front and center of this great hall.
A White Jade Coffin is buried there.
The groove under the floor leads precisely to this White Jade Coffin.
At the bottom of the White Jade Coffin, there's an opening. The copious amounts of blood in the groove eventually all flow through this opening into the White Jade Coffin.
Immediately, the entire coffin is surrounded by a strong smell of blood, but the stone bricks on the ground have the effect of blocking the smell, so the people above the ground can't detect the pungent scent of blood from below.
After all the blood has flowed into the White Jade Coffin, the entire coffin emits a faint light, and the bloody scent around disappears without a trace, as if it has been devoured by the White Jade Coffin.
Meanwhile, inside the great hall.
