| The reservoir bank landslide is one of the commonly occurred landslides.Rainfall and the change of the reservoir water level are two important influcing factors leading to the reservoir bank landslide.It is important to study the influence of rainfall infiltration and reservoir water level change on bank slope stability to avoid bank landslide,disaster warning,and landslide prevention and mitigation.In this paper,the traditional rainfall infiltration model and the calculation formula for determining bank slope saturation line are improved and verified by theoretical analysis and finite element numerical simulation.The influences of rainfall infiltration and reservoir water level change on the bank stability are studied,taking the Huanglongdai Reserior as an example.The main research contents and results are as follows:(1)Based on the analysis of the shortcomings of existing rainfall infiltration models in the assumption of initial soil moisture content,a nonlinear distribution function of initial soil moisture content is proposed,a rainfall infiltration model considering both the slope angle and the non-linear distribution of the initial water content of the soil is obtained,the correctness and reliability of the model are verified by the results of one-dimensional rainfall infiltration test and the monitoring data of water content of Badong Loess landslide in the Three Gorges reservoir area.(2)The shortcomings of the existing formula for calculating the saturation line in considering the diversity of influencing factors are improved,the calculation formulas of the saturation line considering the combined effect of rainfall and reservoir water level,the hysteresis effect of the saturation line and the inclination of the water-resisting floor are derived,the correctness and reliability of the improved formula are verified by the numerical simulation,the measured groundwater level of the farm steep slope near the dam bank in the Longyangxia reservoir area and the measured saturation line of the Zhaoshuling landslide in the Three Gorges Reservoir area.(3)Based on the improved rainfall infiltration model and the improved infiltration line formula,the Morgenstern-Price method is used to analyze the stability of Huanglongdai reservoir slope under the condition of possible rainfall and variation of reservoir water level,the results show that the Huanglongdai reservoir slope is relatively stable under all working conditions.Comparing the results of theoretical calculation with those of numerical simulation,it is found that the Stability Coefficient of theoretical calculation is less than that of numerical simulation under rainfall conditions,while the Stability Coefficient calculated by theory is basically the same as that obtained by numerical simulation under the condition of changing reservoir water level.(4)The dynamic changes of the saturation line and the stability of the Huanglongdai reservoir slope under the action of rainfall and the change of water level are studied by using the SEEP / W and SLOPE / W modules in the finite element software Geo Studio,the variation laws of saturation line and stability coefficient under different rainfall intensity,rainfall duration,water level rising rate and falling rate are obtained.The research results are helpful to accurately understand the mechanism of landslides caused by rainfall infiltration and reservoir water level changes,and to carry out calculation and evaluation of slope instability. |
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