Abstract: As the hydro-fluctuation belt of 30 meters high in the Three Gorges Reservoir area becomes fragile and sensitive, the bank slope’s rock mass quality and its deterioration rules are increasingly becoming a research focus. In this paper, a typical siltstone rock slope in Badong segment of the Three Gorges Reservoir area was selected as a research object. Uniaxial compression test and slake durability test on siltstone samples were carried out by means of drilling in-site, in-door machining and wetting and drying cycles. The test results suggest that siltstones in the research area belong to hard rock, and its uniaxial compressive strength reduces along with the increase of cyclic number. However after 20 cycles of wetting and drying, the strength of siltstone weakens and displays the characteristics of soft rock. Moreover, the siltstone has high slake durability, and the slake durability index (I_d) is in logarithm function relationship with the wet-dry cycle number (N), which means that I_d reduces with the increase of N, and the decrease of I_d gradually slows down along with N increasing. Meanwhile, in the presence of the same cyclic number, the higher elevation siltstone samples come from, the lower I_d value they have. These research results could be reference for obtaining the deterioration rules of rock mass and rock slope stability analysis in the hydro-fluctuation belt of Three Gorges Reservoir area.

Key words: Three Gorges Reservoir area, bank slope, fluctuation zone, siltstone, wetting and drying cycle, deterioration