This item has been removed from the game and can no longer be aquired with the chat command "/give bigshovel"
The big shovel is an upgrade to the normal Shovel, and allows the user to pick up a total of 10 blocks from the ground before needing to drop them off in a storage, unlike the normal shovel which allows only one block at a time.
Using a big shovel, just like the normal shovel, costs 20 base calories, but drops to 17 with Laborer level 1.
The Big Shovel was meant to be a temporary item, and in Alpha 0.5.6 was be taken out in favor of the new stockpile system.
Big Shovel item details as of Alpha v6.3.1.