super-heavy          
adjective (also superheavy) uk/ˌsuːpəˈhev.i/ us/ˌsuːpɚˈhev.i/
 超重的;过重的
weighing much more than normal, and needing a lot of effort to move or lift
  Super-heavy trucks are to be allowed on the country's roads. 该国将允许超重型卡车在道路上行驶。 
 Superheavy backpacks may harm children's growing bones and joints. 过重的背包可能会伤害儿童正在发育的骨骼和关节。 
  chemistry, physics specialized(化学元素)超重的 
A super-heavy element is one that has a higher atomic mass (= the amount of substance contained in the smallest unit of a particular chemical element) than uranium
  Not many labs have the necessary equipment to do work on super-heavy elements. 没有多少实验室拥有必要的设备来做超重元素方面的工作。 
 - More examples
 - I've tried a lot of pans, including super-heavy iron ones.
 - The super-heavy tanks were believed to be indestructible.
 - Scientists at the lab have developed a new method of making super-heavy elements.