Numerical analysis method for piping phenomenon

Abstract

The invention discloses a numerical analysis method for the piping phenomenon. The method comprises the steps of obtaining a seepage deformation similarity criterion on the basis of a fluid dynamics similarity criterion combined with alternate force acting item of medium on fluid; building a microscopic particle model on the basis of the seepage deformation similarity criterion combined with a particle flow method, wherein the model is consistent with a prototype in gravity horizontality; generating skeleton and filling particles under the conditions of zooming particle size distribution and maintaining the same porosity; conducting piping process simulation on the model, and outputting parameter information inside the model when the filling particles in the model reach the balance state or the skeleton particles are damaged; obtaining the actual numerical value by combining the seepage deformation similarity criterion with the parameter information inside the model, and feeding the actual numerical value back to the prototype so as to analyze the piping phenomenon. The numerical analysis method for the piping phenomenon conforms to the Darcy law and the non-Darcy law, the model can truly describe the prototype when two flow states exist at the same time, the problem that a conventional model or a centrifugal test cannot achieve same-ratio zooming of the particle diameter and the model is solved, and analysis is accurate.

Description

technical field [0001] The invention relates to a numerical analysis method for piping phenomena, belonging to the technical field of civil engineering. Background technique [0002] China is one of the countries most severely affected by floods in the world, and floods in the middle and lower reaches of the Yangtze River are particularly frequent and severe. Damage to embankments includes various forms such as piping, flooding, bank collapse, and overall instability. A large number of flood disaster data show that embankment foundation piping is the most harmful. When piping damage occurs in embankments, the seepage field has strong spatial characteristics. There are few studies on the spatial characteristics of the seepage field. The reason is that, on the one hand, the current understanding of the mechanism of piping is not deep enough; on the other hand, due to the complexity of the hydraulic conditions of the project, the analysis of the seepage field is relatively diff...

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Problems solved by technology

In the centrifuge test, if a reduced particle size is used for the test, there will be a problem: the diameter range of the prototype particle is in the range of sandy soil, and after the ratio of particle size to model length is reduced year-on-year, the particle size may already be in the range of clay, while When seepage occurs in clay and sandy soil, the force between soil and water faces a large difference. There may be strong and weak binding water on the surface of clay, but this situation does not exist in sandy soil, that is, using Although the method of year-on-year reduction of particle size achieves similarity in mechanism, the influence of physical and chemical effects in the mesoscopic category is likely to make the results different from expectations; at the same time, the selection of scale relationship is used to ensure that the model and the prototype At the same time, the difference in mechanical properties between the prototype soil and the model cannot be eliminated; it is especially difficult to select a fluid that meets specific conditions

Numerical analysis of piping mostly uses finite element simulation to simulate the seepage field. The continuity method is feasible for the simulation of the relatively stable seepage stage before the piping occurs. When the critical state is reached, the interaction between the geometric properties of the soil and the hydraulic properties caused by particle loss cannot be considered. This complex water-soil interaction cannot fully explain the mechanism of piping

The complex water-soil interaction in the process of piping determines that the development of piping is a nonlinear dynamic process. At present, there is no recognized most suitable research method and theory

Scholars have begun to try to track and record the entire process of sand piping by using microscopic camera visualization tracking technology combined with digital image recognition and analysis methods, and reveal that water-soil interaction runs through the entire process of piping development from the microscopic level. However, this technology only Limited to the indoor test level, it is not yet adaptable to the analysis of the actual piping seepage damage process

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