泥石流泥舌动力学模型研究

The formation and development of scour pit downstream of debris flow sabo dam is one of the most critical dynamical problems during moving bed erosion process, which determines the safety of the dam and the parameters of auxiliary dams other energy dissipation facilities. The early studies indicate that dynamic model of mud tongue is the key problem for the establishment and the ultimate shape of the scour pit. However, it's few researches have been done about this. Therefore, this project focus on the dynamic mechanism of debris flow mud tongue, studying the spatial and temporal evolution characteristics firstly. Based on mechanical theory, the application plans to Multi field coupling analyze the velocity field, the concentration field, and the stress field of the non-Newton and non homogeneous and unsteady fluid. Then to establish the dynamic model of debris flow mud tongue combined with , which include, combined with different initial and boundary conditions. On this basis, to build numerical simulation model by SPH, so that to simulate the kinetic characteristics of debris flow and its dynamic changing process. At last, to verify the dynamic model and the numerical simulation model by a serial flume experiments. This study's focus is the exploration to the basic theory, so that to solve the critical scientific problems in the forming process, mechanism of dynamic and the ultimate form like the dynamic process of the impact of mud tongue as well as fluid solid coupling in the scour pit. This project can guide the design of mitigation engineering's foundation.

泥石流坝后冲刷坑的形成与发展是泥石流动床冲刷过程中最关键的动力学问题之一，其过程与终极形态直接关系到泥石流拦挡坝的安全及副坝等消能防冲设施设计参数的确定；前期研究发现，泥舌的动力学机制是控制冲刷坑形成过程及终极形态的关键问题，但目前尚无相关研究报道。本研究以动力学为核心，在对泥舌形态时空演变特征进行分析的基础上，基于力学理论重点对非牛顿非均质非恒定泥石流泥舌速度场、浓度场、应力场进行多场耦合分析，结合初始条件和边界条件，创建泥石流泥舌的动力学理论模型。在此基础上，构建光滑粒子流数值仿真模型，模拟分析泥石流泥舌动力学特征及动态变化过程。开展物理模型实验对泥石流泥舌动力学理论模型及数值仿真模型进行验证。本研究重点在于基础理论的探索，为解明泥石流坝后冲刷坑形成过程、动力机制及终极形态研究中必须解决的泥石流泥舌冲击力动态过程、坝后冲刷坑内的流固耦合等关键科学问题奠定基础，科学指导防治工程基础设计。

泥石流拦砂坝下游局部冲刷是威胁拦砂坝安全运营的危害形式之一，泥石流过坝泥舌下泄断面的形态变化特征和水力参数，泥舌内流速、固体物质的浓度分布，及冲击力分布特征等是制约泥舌冲击特性和拦砂坝下游冲刷研究的难点问题。然而，对水舌的下泄形态变化等水力特性和冲击力特征等问题的研究较多，而对泥舌相关问题的研究较少。本项目针对泥石流从拦砂坝坝顶溢流到下游沟床的运动过程，通过水槽实验、理论分析和数值模拟的方法，探讨了不同工况条件下泥舌的形成临界条件、下泄形态及变化特征、内部容重、速度分布特征和冲击力分布特征，并建立了相应的计算表达式。经过团队努力，主要取得以下方面的进展：（1）以过坝泥石流体开始贴附坝体下泄现象为泥舌形成临界现象，提出了对应的流速、单宽流量指标参数为泥舌形成临界条件，建立了泥舌临界条件表达式；（2）探明了泥舌下泄形态特征、纵向厚度、横向宽度、下游入射角等形态参数随沿程的变化特征，单因素分析了泥石流容重、沟床纵坡对形态特征变化的影响；（3）提出了以容重分布为评价指标的泥舌内部物质分布特征，建立了内部容重分布特征表达式；（4）通过对室内水槽实验获取的泥舌冲击力数据进行了分析，探讨了不同实验条件下泥舌冲击力的分布特征及实验条件对泥舌冲击力的影响；（5）建立了泥舌下泄的动力学模型，对不同工况条件下泥石流泥舌的动力学特征及其动态变化过程进行了模拟。本项目研究成果为进一步探索泥石流坝后冲刷坑的终极形态奠定基础，为泥石流防治工程的基础设计提供理论依据。