DAMAGE MECHANISM OF JINPING Ⅰ HYDROPOWER UNDERGROUND STATION

Jinping Ⅰ hydropower underground station which buries in a depth of 350m,locates in marble strata. Varies failure phenomena can be found in surrounding rock under high ground stress during excavation process. Based on detailed description of those phenomena,obvious regularities are concluded and described as follows: fracture in top arch of underground station and voltage transformation station downstream sidewall; buckling in top arch of bus bar line cavern and penstock downstream plat part. At last why the anchor over load is explained using numerical simulation results that the radial force is far over the rockmass strength．