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在非饱和多孔介质渗流分析中,近饱和条件下物理模型与数值模型之间的差异会导致数值不稳定问题。为解决这一问题,并保证模拟结果的可靠性,提出了3种方法,并在有限元分析程序U-DYSAC2中分别进行了程序代码的实施。通过数值试验与试验数据的比较,证实了在近饱和条件下土-水特征曲线和水力传导函数的高非线性可引起数值收敛性、稳定性和精度问题,而且在不同条件下含水率和基质吸力的预测结果差异明显。在3种方法中,修正的Van Genuchten模型(MVGM)方法对含水率的预测较为准确,而Line方法对基质吸力的预测较为合理。因此,解决在分析近饱和条件下非饱和多孔介质渗流问题时,为获得接近真实的模拟结果,采用合适的数值方法进行预测是非常关键的。
In unsaturated porous media seepage analysis, the difference between the physical model and the numerical model under near-saturation conditions leads to numerical instability problems. To solve this problem and to ensure the reliability of the simulation results, three methods are proposed, and the implementation of the program code is carried out respectively in the finite element analysis program U-DYSAC2. The comparison between numerical and experimental data shows that the high nonlinearity of soil-water characteristic curve and hydraulic conductivity function under near-saturation conditions can cause numerical convergence, stability and accuracy problems. Under different conditions, the water content and matrix The difference between the predicted results of suction is obvious. Among the three methods, the modified Van Genuchten model (MVGM) method predicts the water cut more accurately, while the Line method predicts the matrix suction more reasonably. Therefore, to solve the seepage problem of unsaturated porous media under near-saturated conditions, it is very crucial to adopt suitable numerical methods to obtain near real simulation results.