Abstract:In order to research the strength properties of altered granite rocks, the samples of mine underground excavation site was selected and the physical parameters of mineral composition, porosity, slake durability and point load strength were tested on those samples with different altered-degrees. Then the correlation between the physical parameters and the strength properties of altered granite rocks was analyzed. The results showed that the physical and mechanical properties of sample No.1 are better than samples No.2’s and No.3’s. Among the mineral compositions, quartz and feldspar have greater influence on the strength of sample No.1, while chlorite and montmorillonite have greater influences on the strength of samples No.2. The rock strength of altered granite increases linearly with the increase of the density, while the strength decreased with the increase of moisture content, water absorption and porosity. Greater effect was revealed on the rock strength when those parameter was in a lower values range.In another aspect, the increase of slake durability is beneficial to the rock strength, the effects on the strength would be more obvious when those parameter was in a higher value range. The results could provide experimental supports for further analysis of the stability of altered granite rocks.