非均质泥石流形成过程动力学模型研究

Recently, with global climate changes and the frequent activities of the earth's crust, the trend appears that the debris flow disasters areaggravating in China, which has highly attracted people's attention. Focusing on non-homogeneous debris flow (solid-liquid two-phase continuous flow) commonly existing in China, simulation experiments for the formation process are about to be carried out to investigate the particle starting of various grain sizes , the dynamic process of fluidization and its features, and based on these to reveal the mechanical mechanisms of particles separation and solid-liquid two-phase separation processes. Based on the theories of sediment movement mechanics,erosion dynamic and soil dynamics, the dynamic expressions of the formation process can be drived out according to the experimental data to further study the energy transformation law referring to the energy linear theory, and finally to establish the dynamic model for the formation process of non-homogeneous debris flow. Furthermore, measured data of Jiangjia gully will be applied to confirm and perfect the models of mechanical mechanism, which can realize the dynamic simulation of the formation process for non-homogeneous debris flow ultimately. The results of this project could not only enrich the contents of both environmental hydrodynamics and the debris flow subject, but also provide technical support for scientifically forecasting the debris flow disasters and control projects layout for non-homogeneous debris flow, which are of great significance for debris flow disaster prevention and mitigation.

近年来随着全球气候变化及地壳活动频繁加剧，我国泥石流灾害尚有加重之势，泥石流问题已受到了人们的高度关注。本项目明确以我国普遍存在的非均质泥石流（连续两相流）为研究对象，首先通过泥石流形成过程模拟实验，研究非均质泥石流形成过程不同组分颗粒起动、液流化动力学过程及特征，揭示粗细颗粒分选分相过程的力学机制；基于泥沙运动力学、侵蚀动力学、土力学等理论方法，结合泥石流模拟实验成果，建立泥石流形成过程动力学关系式，并进一步应用能量线性理论探究泥石流形成过程的能量转化规律及平衡方程，从而构建非均质泥石流形成过程的动力学模型；并应用蒋家沟等实测资料对动力学模型进行验证与完善，最终实现非均质泥石流形成过程的动态模拟。本项目研究成果不仅可丰富环境流体力学及泥石流学科的内容，而且为合理布置泥石流防治工程及科学预报泥石流灾害提供科技支持，对泥石流防灾减灾具有重要意义。

本项目研究以我国普遍存在的非均质泥石流为研究对象，基于非牛顿体动力学模型、固液两相流模型以及能量耗散理论等多学科理论，对非均质泥石流形成过程动力学问题进行了系统模拟实验和理论研究，通过分析非均质泥石流形成过程中流速、水位、容重、孔隙水压等水力泥沙因子沿程变化特点，揭示非均质泥石流形成过程中的泥石流颗粒起动、颗粒混掺和固液两相流形成三个阶段的动力学特征，并运用SPSS等工具软件对影响泥石流颗粒起动的主要因子的贡献度由大到小依次排序为：土体初始含水量、土体颗粒铺设方式、坡度、流量、中值粒径，对影响泥石流流速因子的贡献度由大到小依次排序为：流量、坡度、土体颗粒铺设方式、土体初始含水量、中值粒径。通过分析沿程孔隙水压力和堆积物级配的变化特点，揭示了非均质泥石流形成机理以及孔隙水压力达到峰值时诱发大规模泥石流起动规律；基于shields数及床面切应力力学分析方法，建立了非均质泥石流形成起动判别式；根据实验中流速、水深、容重等观测数据绘制了泥石流形成过程能量分布曲线，分析泥石流形成过程中势能逐渐转化为动能特点，揭示总能量不变、但在堆积区能量耗散显著衰减的规律；最后基于光滑粒子流法（smooth particle hydrodynamics，SPH）初步建立非均质泥石流形成过程动力学模型，并结合蒋家沟等野外观测实验数据加以验证和应用。本项目研究成果对丰富泥石流学科内容及提高我国泥石流监测预报与防灾减灾水平具有重要现实意义。