ABSTRACT
In the last twenty years, lots of large underground structures have been built in China for hydropower stations, pumped storage power stations, oil storage projects and other projects. Firstly in this chapter, large underground cavern groups constructed to house hydropower generators are mainly discussed from five aspects: the geological environmental conditions; the structural system; the construction organization and factors that influence it; the timeliness of the excavation and unloading of the surrounding rock; and the investment and stability controlling standard of large underground cavern groups. Secondly, the engineering problems of large underground cavern groups that have been built in the southwest of China are analyzed from the point of view of their layout; excavation; failures caused by rock mass structures or stress or both; deformation stability of rock anchor beam; overload or failure of anchor cables; unloading and timeliness deformation of sidewall. Regarding the layout of underground cavern groups, the longitudinal axis orientation, space between caverns, rise span ratio and layout form of different huge projects with high in situ stress were collected and are compared. Thirdly, the excavation and supporting design methods of large underground cavern groups, which have been used recently in China, are introduced. Then the typical research progress of large underground cavern groups – such as the intelligent analysis and optimal design method for large underground cavern groups, deformation management classification, and deformation predicting methods for the surrounding rock during excavation – are recommended. Finally, several research prospects for large underground cavern groups are proposed.
