With the influence of so many cracks, the strength, stiffness and stability of the umbrellaarch is decreased greatly, which endangers the operation of underground power house.
数目众多的纵、横向裂缝已大大削弱了混凝土顶拱的强度、刚度及稳定性，危及地下厂房的安全运行。
2
The umbrella shaped cover is one of the fixed tank covers, which is characterized between the conical cover and the arch cover .