流动强度和边壁效应对黏性泥石流流速横向分布的影响机理研究

Velocity distribution is one of the most significant content for debris flow dynamics study. Coupling between boundary constraint and the fluid property, the velocity of debris flow has lateral distribution. At present, a theoretical model for the velocity lateral distribution can derive from the rheological equation of debris flow, however, the model has following questions: the rheological equation is determined based on testing debris flow slurry without coarse particle, and it ignores the effect of flow intensity. Meanwhile, the model cannot apply to all boundary conditions. In this study, we aim to investigate the velocity lateral distribution of viscous debris flow, which mainly include the width of flow plug and the feature of the velocity lateral distribution near the sidewall. Firstly, according to the rheological experiment of viscous debris flow containing some coarse particle, the rheologic equation of viscous debris flow is determined, and a more practical theoretical model for the velocity lateral distribution is deduced. Then, the width of the flow plug and the feature of the velocity lateral distribution near the sidewall are analyzed by flume experiment, and according to the experimental results, a calculation model of the flow plug width and the velocity lateral distribution near the sidewall is determined by revised the theoretical model. The studies of this proposal are expected to provide the foundation for a better understanding of lateral velocity distribution for viscous debris flow, which can facilitate the calculation of the kinematic and mechanical parameters used in debris flow mitigation.

流速分布是泥石流动力学研究的重要内容之一，在两侧边壁约束和流体性质共同作用下，泥石流流速呈现横向分布。目前利用泥石流运动模型方程可推导流速横向分布理论模型，由于运动模型方程主要通过细颗粒浆体流变实验确定，以及理论模型未考虑流动强度和边壁效应的影响，使其难以达到实用要求。本项目针对上述问题，围绕黏性泥石流流体中心附近的流核宽度和边壁附近非等速流动区流速横向分布特征两个核心内容，首先通过开展含粗颗粒的泥石流流变实验，构建泥石流流变模型，结合理论分析，建立黏性泥石流流速横向分布理论模型。然后通过室内实验，揭示流动强度和边壁效应共同作用对流核宽度和非等速流动区流速横向分布的影响规律，并通过修正理论模型建立考虑流动强度和边壁效应的流核宽度计算方法和非等速流动区流速横向分布计算模型。通过本项目的研究，可深入揭示黏性泥石流流速横向分布规律，为准确估算泥石流减灾实践涉及的运动和力学参数提供科学依据。

泥石流流速分布是泥石流动力学研究的重要内容，它关乎泥石流平均流速、流量、冲击力等运动和力学参数的计算，研究泥石流流速分布特征可为泥石流防治工程设计、风险评估、危险范围预测等工作提供理论支撑。泥石流流速分布受流动状态和边壁条件的共同影响，如何描述不同流动状态和边壁条件下流速分布特征是亟待解决的科学问题。项目以黏性泥石流流速横向分布为研究对象，采用理论分析与模型实验相结合的方法，研究流动强度和边壁效应对黏性泥石流流速横向分布的影响，具体包括：（1）通过理论分析，构建黏性泥石流运动物理场景，结合Herschel-Bulkley模型，建立黏性泥石流流表面流核宽度计算方法方和非等速流动区流速表达式；（2）通过自制泥石流模型实验槽，开展室内水槽实验，研究不同坡度、断面宽深比、边壁粗糙度条件下黏性泥石流表面非等速流动区的变化特征，揭示流动强度和边壁效应对非等速流动区流速分布的影响规律；（3）通过室内水槽实验，研究不同坡度、断面宽深比、边壁粗糙度条件下黏性泥石流表面流核宽度的变化特征，揭示流动强度和边壁效应对流核宽度的影响规律。