Dynamic Stability Analysis Of High Earth-rockfill Dam And Research On Reinforcement Technology

The analysis of the stability of high earth-rockfill dam under earthquake is important to the safety of dam. Previous research indicates that upper part is failed firstly when earth-rockfill dam is damaged under strongly earthquake loading, rockfill in upper part is unstable because of whiplash effect. So it is necessary to take earthquake-resistant measures to high earth-rockfill dam. Cable, soil nail, geogrid, etc. are widely used in stabilizing structure of slope reinforcement. However the mechanical character of contact surface between reinforced components and soil mass is complicated, studies on theory of these structure are delayed greatly than their applications. For theses reasons, it is pressing and significant to strengthen theorictical study and set design criterion. The work in this thesis is supported by the science and technology project of National Power Company(Study on calculation theory dynamic response and earthquake-resistant measures of Nuozhadu core rock-fill dam. No. SP11-2002-03-50) and relative horizontal projects. The main aehievements and highlights of the dissertation are asfollows:(1)There are several built-in materal models in FLAC^3D. But the nanshui model, which is widely used in the geotechnical engineering field, is not included in it. Which limit the application of FLAC^3D greatly. In order to fetch up this shortage, Utilizing the further developing platform, the Nanshui constitutive model is developed in FLAC^3D with Visual Studio 2005 environment.(2) Dynamic analysis is done to Nuozhadu rockfill dam, based on the static analysis using Nanshui model developed in FLAC^3D. Results show that, the maximum acceleration appears in the top of the dam and the maximum value is 7.9 m/s², the permanent displacement is 1.1 m. The macro breakage property behaves as the top area of the dam slides along the shallow area of the slope. To strengthen the stability of the dam, it is necessary toresort to some relevant reinforcement measures.(3) A new slope stability analysis method, explicitly satisfying all limiting-equilibriumequations is presented. To make the problem statically determinate variational approach is used. In this approach, the normal stress and the critical slip are got by solving the Euler's equations. The minimum factor of safety for the critical surface is sought and obtained mathematically. A simple numerical routine, which can attain the safety factor for anisotropic soil slope is compiled. The critical slip surface can be automatically drawn by computer.(4) Through the numerical simulation of the reinforced dam by finite difference method, factors which might have effect on reinforcing effect are discussed, such as anchorage mode, cable space, cable length, prestress. At the same time, A new function is proposed for evaluating shear force in cables. Through the calculation of nuozhadu rockfill dam, result shows us the shear force of cable place an important role in mainting stability of slope.(5)According to the previous research, pulling out resistance of geogrid is superior to that of steel bar. Based on geogrid reinforcement theory, concrete framed beams are laid in 3/4 height upwards of earth-rockfill dam, Taking into account for the interaction between concrete frame and soil, a simple model of frame beam is put forwarded.