| The sudden change of river water level and long-term rainfall and other external factors are the main causes of the bank slope failure.Therefore,in order to better understand the failure mechanism of the bank slope deformation and select reasonable bank slope prevention measures,it is necessary to study the influence of relevant factors on the bank slope deformation and failure.In this paper,the deformation and failure mechanism,seepage process and stability of the bank slope of zhoujiayan section of Longfeng River are quantitatively analyzed and evaluated by means of field investigation and monitoring,theoretical model analysis and numerical simulation.This paper focuses on the impact of external environmental factors on the studied bank slope,it discusses four actual conditions,namely,natural condition(183m of constant water level),rainstorm condition,flood level surge condition(198.01 m of the the 5-year return period,203.21 m of the 20-year return period,206.01 m of the 50-year return period)and flood level sudden drop condition.The main work of this paper is as follows:(1)The deformation failure mode of Longfeng bank slope is analyzed.The deformation and failure of the bank slope in the study area are affected by topography,geological structure,stratum lithology,hydrological conditions,human engineering activities and so on.According to the analysis of the failure mechanism and the deformation signs of the bank slope,circul arc silding occurs in the soild body and results in an unstable state,it is determined that the failure type of the bank slope is integral push failure.(2)Using Madis GTS NX finite element software,the original three-dimensional model of the bank slope of zhoujiayan section of Longfeng river is established.The change curve of safety factor and relevant seepage parameters of the bank slope under different working conditions are obtained.The influence effects of different conditions are analyzed,and the results are compared with the results of the theoretical model calculation to verify its reliability.The seepage situation of the bank slope in zhoujiayan section of Longfeng River under different conditions is simulated by using geo studio finite element software,and the influence of various conditions on the seepage in the bank slope is analyzed.(3)According to the characteristics of rapid fluctuation and large variation of river water level in the study area,the influence of the sudden change of water level on the stability of bank slope is discussed in the theoretical analysis.Four kinds of theoretical calculation models are established to obtain the relationship curve between water level difference and safety factor in case of water level sudden change,and then analyze the influence of this factor on the stability of bank slope.(4)According to the actual analysis results,the corresponding control measures are put forward.According to the actual situation of different bank slopes in the South and North sections,the old filling area in the north section should be treated with "cut load reduction + grading slope + grading support + slope grid protection + grass planting +interception and drainage",and the new filling area in the south section should be treated with "cut load reduction + grading slope + anti slide pile + slope grid protection+ grass planting + interception and drainage".At the same time,Midas GTS NX finite element software is used to model and analyze the bank slope after treatment under various working conditions,compare and evaluate the effect of treatment measures,and predict the change of stability of the bank slope after treatment under extreme working conditions. |
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