a gate that can be opened or closed to control the flow of water on a river 防洪闸门；泄水闸门 - (figurative)
If the case is successful, it may open the floodgates to more damages claims against the industry (= start something that will be difficult to stop). 如果本案胜诉，就可能有更多的人向这个产业提出损害索赔，从而一发不可收拾。 🔊🔊
- (figurative)