堤坝管涌的室内试验与颗粒流细观模拟研究

本文对水流垂直方向的堤坝管涌现象分别进行了室内模型模拟和颗粒流模拟实验。在室内模型试验模拟中采用先进的数码成像跟踪设备在细观的尺度上对土样在管涌发生发展的全过程进行了观察和记录,为颗粒流细观模拟提供了必要的细观参数及宏观依据。提出的二维孔隙率与三维孔隙率转换的关系公式很好的将室内模型试验的孔隙率同颗粒流数值模拟结合,运用颗粒流程序采用固液耦合的分析模型对管涌现象作进一步的数值模拟分析。根据模拟结果,分析了管涌产生、发展在颗粒细观尺度的原因,对管涌产生发展中的试样细观变化规律及流速的变化规律进行了分析。这些结果为PFC2D在渗流和渗透破坏等方面的深入研究应用提供了一定的实用依据,同时也为在细观尺度上解释和分析管涌现象提供了一条新的途径。

Study on mesomechanical simulation of piping with model tests and PFC2D

Vertical piping of a dam is simulated by means of model tests and PFC~(2D) software.Piping is observed and recorded from the perspective of mesomechanism using advanced digital photography tracking equipment during the model test.Change in some parameters,such as void ratio and diameter of running out particles,are summarized.The model test offered PFC~(2D) mesomechanical parameters and macroscopical reference.Formula describing void ratio transform from three dimension to two dimension are deduced,which combines the PFC~(2D) simulation of void ratio with the model test.A solid-liquid coupling analyzing model is introduced for the numerical analysis of piping.Occurrence and development mesomechanism of piping is deduced,and changes in soil sample and fluid velocity are analyzed.The results provide a practical basis for the further application of PFC~(2D) in the field of seepage and seepage erosion,and also provide a new way to explain and analyze the piping phenomenon from the perspective of mesomechanism.