Upheaval is a very interesting word. But from what I have learned so far, it cannot be used to convey a positive situation. Let's take a look at the synonyms for example, they are disturbance, chaos, trouble, uproar, etc and the opposite of Upheaval calmness or tranquility. For me, I do not think that it can be used to employ it with a positive connotation, but it can be possible. Hello Mouna, I hope that answers your question. If you'd like to practice more vocabulary, I'd be happy to help you develop a study plan. Feel free to look at my teaching profile and class offerings and send me a message if you think I can help you :-)