单裂隙内浆液基本流动规律的理论、试验、模拟对比分析

Theoretical,experimental and numerical analysis of fundamental flow laws of grout in single rock fractures

工程中广泛使用的水泥浆液是一种非牛顿流体,在裂隙内扩散时表现出复杂的宏观非线性渗流特征,在细观流场上也因屈服应力的作用呈现出柱塞流等特殊流动现象。配制符合Herschel-Bulkley(H-B)模型的模拟浆液,利用粒子图像测速(particle image velocity,PIV)技术开展平直裂隙内的可视化渗流试验,同时求解H-B-P(H-B-Papanastasiou)方程开展浆液渗流有限元数值模拟。基于平直裂隙中单相屈服幂律流体渗流解析解,从理论、试验、模拟相结合的角度分析了平直裂隙内注浆压力与流速的非线性关系;通过对流速剖面图的对比,分析了H-B流体的柱塞流特征;通过与Bingham模型的对比证明了H-B流体更符合实际浆液流动规律。通过原创的可视化测试手段验证了理论和数值模型,提出了参数取值依据,对提升复杂工程岩体中的注浆工艺具有参考价值。

Cement grout,commonly applied in engineering,is a type of non-Newtonian fluids,which exhibits complex macroscopic nonlinear flow characteristics when diffusing in fractures and presents special structures such as plug flow due to the existence of yield stress.This study involved preparing artificial grouts following the Herschel-Bulkley(H-B)model and conducting visualization grouting tests on flat fractures using particle image velocity(PIV)measurements.Grout flow numerical simulations were performed using the finite element method(FEM)to solve the H-B-P(H-B-Papanastasiou)equations.The nonlinear correlation between pressure gradient and flow rate was theoretically,experimentally,and numerically analyzed and confirmed using the analytical solution of the single-phase yield-power-law for fluid flow in flat fractures.Plug flow features of H-B fluids were examined by comparing velocity profiles obtained through various methods.Comparison with the Bingham model proved that the H-B model aligns better with real grout flow.This study comprehensively verified the theory and numerical model based on an originally developed visualization method and laying the groundwork for parameter determination,which may help improve the grouting technique in complex engineering rock masses.