基于颗粒分选机制的碎屑流运动特性研究

Different from the traditional landslide which moves like a rigid body, the granular mass flow exhibits typical flow of loose debris media, and its mobility depends on the complex interaction mechanism of particles. Meanwhile, particle segregation can induce the internal structure judgment, significantly affects the mobility and deposition of granular mass flow, it’s mechanisms of action, however, is still unclear. Based on the strategy combining the “macroscopic runout characteristic of granular mass flow” and “microscopic particle interaction mechanisms”, the applicant will adopt the physical model test and particle distinct element method to study the evolution of particle segregation together with different grain and basal characteristics. In addition, the evolution of friction and collision of particle and flow regimes are revealed, and the quantitative expression between the basal resistance term and the local particle volume fraction, shear rate and normal stress is established. Furthermore, based on the particle mixing theory, the dynamical model of granular mass flow considering the particle segregation are established for predicting the particles’ moving trail, shifting law and danger region. The research achievements can help us understanding the runout and non-linear deposition characteristic of granular mass flow, and provide theory and technical supports for the prediction and prevention of mountain hazards and regional planning.

与传统滑坡的似刚体性质不同，碎屑流表现为松散颗粒介质流动，颗粒间相互作用是碎屑流运动的关键。同时，颗粒分选效应会引起内部结构调整，对碎屑流运动能力和堆积特征影响显著，但其具体作用方式还不清楚。本项目以“碎屑流宏观运动特性”和“颗粒微观作用机制”相结合为研究策略，通过室内模型实验和颗粒离散元模拟，系统研究颗粒介质特性及基底特征等对碎屑流颗粒分选的影响，厘清碎屑流颗粒分选的主控因素；其次，揭示碎屑流运动的颗粒摩擦、碰撞机制及流态演变规律，建立基底摩擦系数与局部颗粒含量、剪切速率和应力状态等参数的量化表达。在此基础上，基于颗粒混合理论，建立碎屑流动力演化过程的物理模型，有效地预测碎屑流灾害运动轨迹、迁移规律和致灾范围等。研究成果将有助于深入理解碎屑流运动特性及非线性堆积特征，为我国山地灾害预测、防治和区域规划提供理论和技术支撑。

以碎屑流灾害为研究对象，基于颗粒介质力学特性，通过理论分析、室内模型实验及数值模拟等多种技术手段，系统研究了颗粒介质特性、基底倾角、粗糙率等参数对颗粒分选-扩散掺混过程的影响，揭示了碎屑流颗粒分选作用机制。进一步，建立了碎屑流颗粒分选的数学控制方程，搭建了具有自主知识产权的碎屑流运动预测分析平台LAN-R。通过算例分析，定量评价了碎屑流运动轨迹、迁移规律和致灾范围等，揭示了颗粒分选对碎屑流运动特性的影响；此外，基于双层流模型与能量守恒理论，分别建立了碎屑流动力学模型，可为碎屑流运动特性提供新的思路。研究成果将有助于理解碎屑流复杂的运动特性及非线性堆积特征，深层次揭示碎屑流基底刮铲导致规模放大效应的溯源机制，同时加深对大型滑坡转为碎屑流所体现出超强运动能力的认知，从而为我国山地灾害预测提供理论依据和技术支撑。