The study of the swelling properties of the altered granite by means of large scale field tests for underground excavations of the largest pumped storage power station in China

A brief introduction is given in this paper to the main problem on engineering geology encountered in the underground excavation at Guangzhou Pumped Storage Power Station, i.e. the weak mechanical property and swelling property of the altered granite. The main results of the methods and experiments are given with respect to the swelling properties of the large scale tests carried in-situ of the altered granite. Minerological analysis shows that the content of montmorillonite is closely correlative to the swelling property. The author puts forward a formula to evaluate the swelling pressure of the altered granite and the dynamic expansion mechanism for explaining the damage occurred on the altered granite walls of the underground excavations.