、、。
If it gets bad, cracks can develop or it can even rupture.
Literal
Severe become [when-と], cracks [subject-が] arise-[or-たり], rupture do [thing-that-happens-こともあります].
A follow-up in the same construction/medical register (depending on context — could be talking about pipes, tissue, or similar). ~たり~たりする ('things like X-ing or Y-ing,' 'X, Y, and so on') is the standard way to list non-exhaustive examples of actions or states. Here 亀裂が生じたり、断裂することもあります — 'things like cracks developing, or even rupturing.' Note the mixed grammar: 亀裂が生じたり uses ~たり on the verb, but 断裂する uses the dictionary form directly with こともあります. The whole list is captured by ことがある ('there can be cases where').