When was the last time you visited that area?
Let's analyze your 3 division concrete:
1. I suspect that concrete is located in an area near a sloping edge of a mountain, where rushing water during heavy rain uncover this site.
2. This site was found by a group of treasure hunters (not your group) and open it, probably found some precious metals or treasure. However, nobody knows...
3. But, studying the situation, all covers were opened, meaning, when they first opened the first chamber, probably they found nothing, thus, opening the second chamber, still, it seems they didn't found anything....That is why they opened the 3rd chamber, opening to the point of removing most of the top covers.
4. If the broken chinaware was found on the last chamber, we can assume that it is the last chamber that was opened, in which probably, where the 'good' are located.
5. But if the broken chinaware was found in the center, then we can conclude that there is nothing in it, except chinawares, where for a neophite hunters, not worth to take thus opening the 3rd chamber.
6. Now, If nothing was found in that 3 chambers, considering the facts that it is located in a very unusual place, I suggest you to return back to the area and check again the two images, where I think I saw an X mark on one of its side.
7. There is a probability that if there is any 'object' hidden in that concrete, it is not on the space, but to the side of the walls.
8. Check your pictures carefully, I saw an X mark from it.