Stability Research Of Barrier DAM Caused By Excess Pore Water Pressure Changes Under Earthquake

The article outlines the definition of stability safety factor of the slope, and phylogeny of computing dynamic pore water pressure under dynamic load, static and dynamic slope stability analysis method and slope instability mechanism under earthquake; Secondly, again based on percolation theory and dynamic finite element method,about groundwater flow analysis module SEEP/W which consists of geotechnical dedicated software Geo-Studio, it was described in detail related with its characteristics、the theoretical foundation、its non-saturated hydraulic conductivity、 boundary conditions of seepage analysis、the convergence criterion, and about dynamic response analysis module QUAKE/W, its soil constitutive model、dynamic pore water pressure model、finite element dynamic basic equation、dynamic boundary conditions and iterative convergence criterion of dynamic analysis.For the research, using finite element software Geo-Studio, a numerical model for dimensional dynamic stability analysis of the barrier dam is established, and based on univariate analysis, according to time curve by excess pore water pressure, followed by analysis of variation of the dam excess pore water pressure caused by the change in the basic elements of ground motion, the depth of the water depth upstream, dam geometry parameters, physical and mechanical parameters. At the same time according to the evaluation method of dynamic safety factor proposed by Zhaoying Wu, find out the variation of the dam stability factor due to changes of the impact factor, and in accordance with curvilinear relationship between the two, the sensitivity of each factor for dynamic stability factor is calculated. The results showed:on the sensitivity, upstream slope ratio>height of dam>internal friction angle> PGA> upstream water depth> cohesion> bed dip.Typical examples of M pile gully terminal moraine dam as research, use finite element software Geo-Studio to analyze the distribution changes of excess pore water pressure about Terminal moraine embankment and its upstream slope stability in the case of the role of seismic intensity 7,8,9. The results show:with the seismic intensity increases, the distribution of excess pore water pressure of the dam, up along the slope from the toe and to the center along the bottom, will gradually spread to the central portion. Further development, the value of excess pore water pressure reduces with the elevation increases in the central part of the dam under strong earthquake. As earthquake intensity increasing once, the maximum difference of the excess pore water pressure caused two adjacent intensity becomes much larger under the earthquake intensity.For analyzing dynamic stability of natural earth dam which may appear dangerous situations as soon as possible, based on orthogonal experimental design method, and according to the size of the sensitivity factor, choose greater sensitive factors as experimental factors and use Geo-Studio software to create a rapid assessment form which determinates the stability of natural rock under earthquake; And through checking the table dynamic upstream slope stability factor of terminal moraine dam correspon7、8、9 seismic intensity is 1.566,1.327,1.023. Compared with the simulation results of M pile gully terminal moraine dam, there are some differences, but in the acceptable range, thus the rapid assessment is applied to the decision-making.