| The anti-sliding stability analysis of slopes has always been a significant field in geotechnical engineering.There are already many natural slopes in the Earth.With the requirements of economic construction and social development,the number of slopes related to human engineering activities is quickly increasing.The development of water conservancy and hydropower projects has raised many stability problems of dam foundation,dam abutments and reservoir bank.The stability of them is the key to the construction of hydraulic engineering projects and the post-production operations,which is of great significance to the production and construction of society.Basing on A'hai hydropower station,the main research content of this paper is as follows:(1)For the slope stability analysis by rigorous Janbu method,there is a problem of non-convergence in the calculation when the number of slices is large.Because B-spline has good smoothness,compactness,and clear expression,matrix calculation can be used in the process of solving the interpolation function coefficients,which improves the calculation efficiency and is easy to program.The B-spline interpolation function was proposed in here to simulate the inter-slice moment function of rigorous Janbu method to make the first derivative of the inter-slice moment continuous and derivable.Thereby the safety factor calculation of rigorous Janbu method converges steadily.The calculation and analysis of typical examples show that this method is feasible and reasonable.(2)The engineering geological conditions of A'hai hydropower station were analysed,and the rock mass quality of the project area was evaluated.Based on the analysis results of geological conditions,the failure modes of slopes in hub area and deposit slopes in the left bank front of dam were judged.(3)The typical sections of A'hai hydropower station were selected,and the limit equilibrium analysis of each section was carried out by using the Janbu method described above and M-P method.The calculation results indicate that,for the slopes in the hub area(BH1 and BH2),the safety factor range from 2.206-3.438,which is far larger than the control standard;as for the deposit slope in the left bank front of dam(B6),its safety factor is between 0.865 and 1.167 under the normal water storage condition,which is lower than the control standard of the operation period.The stability of the deposit slope cannot meet the requirements,and engineering measures are needed for disposal.(4)The finite element strength reduction method was applied to further study on the excavation slopes of the hub area,the isochromatic diagrams of the rebound deformation plastic zone and stress caused by the excavation of the slope were given.At the same time,the possible most dangerous sliding surface and the corresponding safety factor were obtained.(5)Two support measures are studied and compared.One is the scheme of anti-slide pile,and another one is the scheme of cutting slope and reducing load.The scheme of anti-slide pile is difficult to carry out according to the geological conditions.With the scheme of slope cutting and load reduction,the part above the storage level is in a stable state,and the part below the storage level is also within the safety standard.So the slope cutting and load reduction is adopted as support measure for deposit slopes in front of the dam.At the end of excavation,the safety factors of sections B4 and B8 is between 1.04 and 1.44,which indicates the slopes are stable. |
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