Research On The Mechanical Characteristics And Deformation Regularity Of Double Curvature Arch Dam Abutment

By means of field research,data acquisition and studying engineering geological environmental conditions,engineering geological classification for rock structural planes of Abutment was established in Baihetan Hydropower Station.Controlling structure surfaces were analyzed and the development characteristics of rock structural planes were systematically studied in the paper.The three-dimensional numerical model was built by the large finite element software.Conditions including the excavation of dam abutment,dam building and normal water level are were simulated separately.The mechanical characteristics and deformation regularity of double curvature arch dam abutment were researched by analyzing numerical simulation results of stress field and displacement field under different conditions.The main research work is as follows:(1)By means of field research,data acquisition and analysis on geological information,the basic engineering geology of the topography,stratigraphic lithology,geological structures and geo stress were obtained and the weathered rock mass and unloading features were analysed briefly in the dam area of Baihetan hydropower station.(2)Rock structure planes were classified and categorized with engineering geology method.The origin of discontinuities and the evolutionary process were explored,the detailed analysis of the development characteristics of structural plane is made.According to the physical and mechanical properties of rock,the influence factor of rock mass quality were proposed.(3)The three-dimensional numerical model of dam abutment was built by the finite element software.The dam abutment was excavated by nine steps according to the designed slope magnitudes.Force and deformation characteristics of rock mass after were simulated under excavation condition in the dam abutment.Comparing and analyzing emulational data with monitor data,both of them proved that results are basically identical.According to the results of simulation,the excavation of dam abutment process disturbed the abutment rock mass to a certain extent,but the stress and displacement values owing to disturbing were smaller.The results affected the stability of arch dam abutment little.(4)The results showed that the process of building the dam had less effect on the stability of arch dam abutment than the process of dam abutment excavation.The local position of steep geography on both sides and the developed weak structural planes had greater deformation.The abutment rock mass was over all stable.(5)Under normal pool level conditions,arch dam transmitted the load on its own to the abutment rock mass on both sides which caused changes of the stress and displacement field.Numerical simulation of stress-deformation characteristics of the abutment rock mass under normal water storage condition was conducted.It shows that the total displacement of abutment rock mass was not large and the abutment rock mass was in a stable state under normal water storage condition.But the influence of dynamic water pressure caused by change of reservoir water level on abutment rock mass on both sides should be focused on,especially the positions of developed geological structure and steep geography.