| With the development of hydropower energy in western mountainous areas and valleys in China,many dumping and destruction problems have been brought under complex geological conditions,which have a great impact on the construction and operation of the project.Nam Tha 1# Hydropower Project is located on the Namtha River,the first tributary of the Mekong River in northern Laos.Affected by blasting excavation,the tensile cracks at the top of the slope gradually develop to the deep,and finally the overall dumping damage occurs.Therefore,the study of its toppling deformation and stability not only provides theoretical basis and technical support for the stability analysis and evaluation of dumping bodies,but also provides important practical application value and theoretical significance for the dam safety of water conservancy and hydropower projects.The results show that:(1)According to the engineering geological conditions of the left bank slope of Nantahe 1 # hydropower station and the structural design of the left bank slope,the failure mode and causes of the dumping deformation are analyzed.Field investigation and discrete element numerical simulation are used to found that the toppling deformation of the left bank slope of Nanta River starts from the natural slope,and has experienced the evolution stage of slope cutting,bending deformation,breaking through and current slope,forming a new current slope.(2)Through the field monitoring system of the left bank slope of Nantahe 1 #hydropower station,the four-year monitoring data since 2018 are obtained,and the basic characteristics of surface deformation and internal deformation of the left bank slope are analyzed.On this basis,the data was reprocessed by using the clustering model and the fitted prediction model,and it was found that the left bank slope showed an overall convergence trend as time increased,except for a slight increase in individual parts.The local shallow surface deformation in the areas of 0 + 58.00 m above the overflow,0 +170.00 m below the overflow(landslide area)and 0 + 335.00 m below the overflow showed a slowly increasing trend,which can be used as a typical profile for analysis.(3)Aiming at the left bank slope of Nam Tha 1# Hydropower Project,the typical geological section is selected,and the calculation method of anti-dip stability is improved based on rigid body limit equilibrium.It is concluded that the safety factor of each calculation section of the slope is greater than 1.29 under natural conditions,the safety factor is greater than 1.20 considering the influence of rainfall,and the safety factor is greater than 1.21 considering the influence of earthquake,which meets the requirements of the specification.(4)Analyzing the slope anti-tilt stability under both natural working conditions and construction working conditions.By selecting the typical geological section of the slope,the numerical calculation model of slope generalization is established.The twodimensional block discrete element program(UDEC)is used to analyze the antidumping stability of the slope under two conditions.It is concluded that after anchor reinforcement,the stress state of the slope surface is improved,which is conducive to reducing the occurrence of tensile cracks on the slope surface,inhibiting the development of slope deformation and lower plastic zone,and reducing the dislocation and opening of rock strata.(5)Based on the mechanism and cause analysis of slope deformation and failure,the spatial and temporal evolution law of dumping deformation,and the anti-dumping stability as the main line,the geological survey,the clustering model K-Means algorithm and FCM algorithm,the fitting prediction model FOS-ELM algorithm,the discrete element difference UDEC,and the improved rigid body limit equilibrium EMU are used to systematically study the mechanism and stability of slope dumping deformation,and a set of whole process evolution and evaluation system of slope dumping deformation is proposed. |
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