基于BP修正流变模型的泥水盾构泥浆流动模型开发及应用

Development and Application of Slurry Flow Model for Slurry Shield Tunnelling Based on BP Modified Rheological Model

  • 摘要: 为提高泥水盾构泥浆成膜质量,维持开挖面稳定性,在泥浆参数设计时,往往需要准确预测膨润土泥浆的流体动力学特征。针对目前泥水盾构泥浆流动模型求解过程中数值发散及计算参数严重依赖经验取值的问题,开展不同膨润土含量下泥浆流变室内试验;基于试验结果,将Bingham-Papanastasiou(BP)修正流变模型嵌入到计算流体动力学(CFD)框架下,开发一种用于泥浆流动模拟的优化数值方法,并通过开展平板间Bingham流体的泊肃叶流动数值模拟,验证该数值方法的有效性和准确性;之后建立泥浆三维管道流数值模型,探究不同流变参数影响下泥浆的管流特征。结果表明:随着膨润土含量的增加,泥浆的屈服应力与稠度系数等流变参数值呈现上升趋势;而流变参数的提高均会使泥浆在地层渗透时产生更多的能量损耗,随着稠度系数k从0.1 Pa·s增大到0.75 Pa·s,压降提高6.21 kPa,此时可以更好地维持泥浆压力的有效转化,提高泥浆成膜质量。

     

    Abstract: In order to improve the formation quality of filter cake in slurry shield tunnelling and maintain the stability of the excavation face, accurate prediction of the rheological characteristics of bentonite slurry is often required in the design of slurry parameters. Addressing the issues of numerical divergence and heavy reliance on empirical values in the solution process of slurry flow models for shield tunnelling, indoor rheological tests of slurry with different bentonite contents were conducted. Based on the experimental results, the Bingham-Papanastasiou (BP) modified rheological model was incorporated into the computational fluid dynamics (CFD) framework to develop an optimized numerical method for simulating slurry flow. The effectiveness and accuracy of this numerical method were validated by conducting numerical simulations of Poiseuille flow between parallel plates with Bingham fluids. Subsequently, a three-dimensional numerical model of slurry pipe flow was established to investigate the pipe flow characteristics of slurry under different rheological parameters. The results show that with the increase of bentonite content, the yield stress and consistency coefficient of the slurry exhibit an increasing trend. Moreover, an increase in rheological parameters leads to more energy loss of slurry during infiltration into the formation. As the consistency coefficient k increases from 0.1 Pa·s to 0.75 Pa·s, the pressure drop increases by 6.21 kPa, which can better maintain the effective transformation of slurry pressure and improve the formation quality of filter cake.

     

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