Abstract: In the aim of investigating the long-term effect of water level fluctuation on slope stability, rock samples from Cangshang open-pit slope in Laizhou City were selected for triaxial creep test under different saturation-dehydration cycles. By analyzing creep strain-time curves and creep rate curves of SγJH, the creep properties of slope rock after saturation-dehydration cycles were explored.Furthermore, SγJH rock samples after different cycles were scanned by electron microscopy to analyze the damage mechanism of rock under water-rock interaction in microscopic scale.Results indicate that, 1) along with the increasing of saturation-dehydration cycles, axial creep strain increased up to 31%, and the lateral creep strain increased by 33% under adjacent cycle times; 2)instantaneous elastic strain of SγJH-15 improved by 54.3% than that of SγJH-0,creep strain at adjacent load level increased by 24.3% and total creep strain of SγJH reached 80% or above of limit strain in triaxial compression test;3) with the increasing of saturation-dehydration cycles, steady creep rate became nonzero and steady rheological rate of SγJH-15 at the fifth level of loading reached up to 29.2×10^-6 h;4)at the moment of applying axial load at all levels,initial creep rate acceleration also increase.In the research field of mechanical properties of rock under water-rock interaction, microscopic weakening and rupture occurs in rock samples under the cycle action due to heterogeneous internal structure of SγJH. Hence the original stress balance is broken, resulting in irregular fluctuations and abrupt change of rock deformation curve.

Key words: water-rock interaction, open pit, rock mechanics, creep test, creep law