(1. Key Laboratory of Geological Hazards on Three Gorges Reservoir Area，Ministry of Education，Three Gorges University，Yichang，Hubei 443002，China；2. Key Laboratory of Construction and Safety of Water Engineering of the Ministry of Water Resources，China Institute of Water Resources and Hydropower Research，Beijing 100038，China)
Abstract：Under the action of the periodic rise and fall of the reservoir water level，the jointed rock mass in the hydro-fluctuation belt of a bank slope has been in a state of soaking-air-drying cycle for a long time. In order to study the damage and deterioration characteristics of the jointed rock mass in the hydro-fluctuation belt，the typical jointed rock mass of a bank slope in the Three Gorges Reservoir area was selected as the research object. In this paper，a water-rock interaction test considering the water pressure fluctuation and soaking-air-drying cycle process is carried out，and the shear mechanical properties and the microstructure damage evolution law of the jointed rock mass are systematically analyzed. The results show that：(1) the shear strength of jointed rock mass under water-rock interaction shows a deterioration trend from steep to slow，which can be divided into three stages. Among them，the degradation range of the shear strength parameters of joint surface caused by the first six water-rock interaction cycles accounts for about 90% of the total degradation range，and the total degradation degree of the shear strength of joint surfaces is about 30% after 10 water-rock interaction cycles. (2) The microstructure damage of the joint surface is significantly deteriorated under water-rock interaction. It gradually changes from a dense state to a loose and porous state. The three morphological parameters of the joint surface，such as the average fluctuation angle，the average relative fluctuation amplitude and the area expansion rate，show a trend of first steep and then slow deterioration. Macroscopically，the roughness coefficient JRC of the joint surface and the strength of the rock wall are reduced，and the coincidence degree of the upper and lower walls of the joint surface is reduced，which leads to the gradual deterioration of the shear properties of jointed rock mass under water-rock interaction. (3) Based on the Clough-Duncan hyperbolic model，a shear constitutive model of jointed rock mass considering the damage of water-rock interaction is established. The verification analysis shows that the model can better reflect the deterioration law of shear mechanical properties of jointed rock mass under water-rock interaction. The relevant research methods and conclusions can provide a theoretical basis for the long-term deformation and stability analysis of reservoir bank slope.
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2023, Vol. 42 
