Study On Rock Deterioration Characteristics Of Reservoir Bank Slope Under The Effect Of Water-Dehydration Cycle

After the completion of the impoundment of the Three Gorges Reservoir,the water level in front of the dam of the Three Gorges Reservoir vary between 145m and 175m.This result in a "falling belt" with an area of up to 400 square kilometers and 30 meters height differences.Rocks in the "fluctuating zone" of the reservoir area suffer from deterioration of their mechanical properties,such as strength and strength,due to the water-saturation-recycling cycle year after year,witch ultimately affect the stability of the bank slope.This paper regards the red sandstone of the reservoir bank slope in the Three Gorges area as the research object,and studies the deterioration of mechanical properties,such as strength,under the effect of the water-saturation and water loss cycle,which provides reference and guidance for practical engineering.The research content and research conclusions are as follows:1.The uniaxial compressive strength,tensile strength,triaxial compressive strength,cohesion,internal friction angle,and elastic modulus of red sandstones are reaserched through a laboratory tests under the effect of the deterioration of the water-loss cycle.The experiment results demonstrated that they are all decrease with the increase of the number of saturated-water loss cycles.2.Based on the laboratory test results,this paper analysis the degradation laws of various mechanical parameters of red sandstone.The results show that the total deterioration rate of uniaxial compressive strength,triaxial compressive strength,cohesion,internal friction angle and elastic modulus mechanical properties of red sandstone increases with the increase of saturated-water loss times,and the total deterioration rate with the increase in water-loss of water increased.Under the same saturation-dehydration cycle number,the total deterioration rate decrease gradually from elastic modulus,uniaxial compression,triaxial compression,cohesion to internal friction angle in order.3.Based on the Hoek-Brown criterion,it introduces the function variable of the saturation-dehydration cycle numbern,which improves the Hoek-Brown criterion.4.The creep test under the saturated water-dehydration cycle deterioration effect was carry.The relationship between deformation,strength,failure morphology,and saturation-loss cycles of red sandstone is obtainly.The whole process of creep characteristics of red sandstone was analying,and a "nonlinear viscoelastic-plastic creep model-NNVP constitutive model" was established.The damage variable was introduced into the established model and the "consider saturated-water loss cycle number" is established.Damaged nonlinear viscoelastic-plastic creep model-DNNVP model.5.By means of FLAC numerical analysis,the influence of reservoir-bank slope stability on bank slope stability was analying.The results show that for reservoir bank slopes that are assumed to consist of intact mean rocks,the saturated water-dehydration cycle degradation is weak,but considering the actual existence of fracture development,weak structural planes,and rock formations with different lithologies The effect of water saturation and water loss on the bank slope will be greatly enhanced.