Study of Huge Explosions / Huge Craters near Donetsk Chemical Plant

Clearly multiple extreme explosions with corresponding large craters appeared in the areas of the Chemical Factory.
That raises the question: WHAT IS GOING ON THERE?

Some possibilities:
1. Does Ukraine regularly bomb it with Tochka-U?
2. Do the Russian have ammunition depots there and something goes wrong every now and then?
3. Do the Russian blow up stuff just to be able to blame Ukraine using Tochka-U and thus have a reason to inflame the conflict again?
4. Are the Russians building, experiment and testing mega-bombs?
5. A combination of the above?

One thing is clear. The numerous wagons there have not moved since May 30th 2014

Therefore it seems unlikely that these are used for transporting ammunition. On the other hand these bunkers and the factory are designed and used for producing and storing ammunition. How much (old?) ammunition was still stored in these bunkers? Could simple shelling have caused a chain reaction and blow up depots?

But then: if ammunition depots are blown up, why again and again? Or do the Russians deliberately blow up large stocks of old ammo there? And intimidate Donetsk residents and make a nice blame-Ukraine story of it?