Glue? Of course it works!
Dioramas aren't meant to be thrown around all over the place, but kept in one place. They don't need to be able to withstand galeforce winds
, models are delicate and unless your model is incredibly precious or heavy, i wouldn't really bother.
Please explain how you're meant to attach a 1/35 jeep with a nut and bolt without it looking like a massive rod going straight up the drivers bum? And how are you meant to conceal the nut/bolt? "Oh its just debris..."
It looks silly!!! If you're really intent on that solid diorama then (this sounds maniacal but it works) blowtorch(lightly) the parts being stuck to the ground and, while still molten, force them down onto your surface. Hey presto! Have fun.
EDIT: Hey if it works with you, no complaint