is just for that... then you can just drop the armored lid... modern VLS is designed that if an explosion happen in one of the missile, while it's still in the silo, it will only damage that silo, all the explosive force, will go out of the top of that silo... the force from an explosion will always take the easiest way, so if you have an armored lid on top, the explosion will take a different rout... into the ship instead of out.
Se for example the German Frigate F-219 Sachsen, when one of the missile exploded during an Naval exercise on the coast of Norway, the only damage they had, was damage to one of the silo and some burnt paint...
They went into Naval base in Norway for an inspection, an there was no damage to rest of the VLS and missiles, but since it's peace time, they just went back home and had it refurbished. (ho would be comfortable, with knowing those missile experienced an high amount of shock!)
There is an nice video of it:
https://www.youtube.com/watch?v=l8TaIP- ... INewsVideo
picture after the missile explosion, and as you can see, only on silo got damaged, that what a modern VLS do: