基于DEM⁃CFD耦合方法的砂土渗透破坏强度劣化模型研究

Degradation Model of Sand Seepage Failure Strength Based on DEM⁃CFD Coupling Method

渗透破坏对岩土类材料的冲蚀是造成土坝、桥梁等水利基础设施破坏的主要诱因之一。为了克服现有试验手段在还原渗透破坏发生发展过程中存在较大缺陷,利用离散元软件PFC3D中CFD颗粒流数值方法来模拟颗粒运移过程,并通过设计标准尺寸的砂柱模型进行模拟试验,结果表明,细颗粒含量对模拟砂柱的影响显著,渗透破坏导致砂柱的峰值强度值和临界强度值下降明显,强度劣化度不断增加。理论推导出DEM⁃CFD耦合劣化模型并加以验证,发现DEM⁃CFD耦合劣化模型可以在砂柱模型中进行渗透破坏过程计算,在整体趋势和计算精度方面也可得到良好的预测结果。研究成果可为渗透破坏引起的土体力学强度劣化分析及水利工程渗透破坏灾害的防控提供参考。

The erosion of geotechnical materials by seepage failure is one of the main causes of damage to water conservancy infrastructure such as earth dams and bridges.Due to the large defects of the existing test methods in the occurrence and development of reduction seepage failure,the CFD particle flow numerical method in the discrete element software PFC3D is used to simulate the particle migration process,and the simulation test is carried out by designing the standard size sand column model.The results show that the content of fine particles has a significant effect on the simulated sand column.The seepage failure causes the peak strength value and critical strength value of the sand column to decrease significantly,and the strength deterioration degree increases continuously.The DEMCFD coupled deterioration model is theoretically derived and verified.It is found that the DEMCFD coupled deterioration model can calculate the seepage failure process in the sand column model,and can also obtain good prediction results in terms of overall trend and calculation accuracy.The research results can provide reference for the analysis of soil mechanical strength degradation caused by seepage failure and the prevention and control of seepage failure disasters in water conservancy projects.