Mechanism of Deformation and Damage of Top Arch During Underground Cavern Construction and Disposal Countermeasures
Sprayed concrete layer is a kind of protective structure commonly used in underground plant cavern group.The phenomena such as cracking,hollowing and falling of sprayed layer materials not only affect the construction safety of underground plant cavern group,but also damage the original support system and bring uncertainty to the stability of underground plant cavern group.Taking the large underground cavern group of pumped storage power station as an ex-ample,the deformation and damage characteristics of the top arch surrounding rock of the main plant were analyzed.The deformation characteristics of the surrounding rock of the cavern chamber and the strength of concrete and its bonding properties were analyzed respectively to clarify the main reasons for the deformation and damage of the top arch and reveal the correlation between the top arch damage area and the peripheral rock significant deformation area.Then,the top arch deformation damage mechanism was divided into two categories:shear damage of spray layer caused by deformation of structural surface and bending damage of spray layer caused by rock erosion.Finally,the disposal countermeasures of top arch deformation damage engineering problems were proposed,which provide reference for the solution of similar engi-neering problems.