Abstract：As hydro-fluctuation belt is the sensitive area of bank slopes，the change law of fracture toughness under the fluctuation of reservoir water level is crucial to the bank slope stability. According to the actual occurrence environment of hydro-fluctuation belt，taking typical sandstone in the Three Gorges Reservoir area as the research object，long-term soaking and immersion-air dry circulation test schemes are designed. The test results show that：(1) Sandstone samples have obvious softening trend under long-term soaking and immersion-air dry circulation. The degradation trends of fracture toughness，tensile strength and compressive strength of sandstone are consistent basically；and the degradation rate is relatively obvious in initial stage，later gentle. (2) The degradation trends of parameters are quite different. And the fracture toughness is the fastest，tensile strength is the second，and compressive strength is relatively slow. (3) Comparing the two schemes，the degradation trends of mechanical parameters of sandstone show more apparent under immersion-air dry circulation，which shows that the action of immersion-air dry cycle can not be ignored in simulating the hydro-fluctuation belt′s water-rock interaction. The research results have important reference value for analyzing the stability of bank slopes exist in reservoir area，and relevant test methods can also provide reference for similar tests.
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2012, Vol. 31 
