Entrainment and Deposition of Surface Material by Particle-Laden Flows: From the Laboratory to the Hillslope

对该项目更广泛的意义和重要性的非技术性描述泥石流是一种动态移动的水、泥、土和大到巨石大小的物体，是滑坡的主要成分。 在陡峭的山坡和山区，泥石流的速度可以超过160公里/小时（100英里/小时），并可以增长到超过20，000立方米（700，000立方英尺），对人的生命和基础设施构成重大危害。泥石流通常开始为相对较小的滑坡，由于沿其路径沿着地表物质，其尺寸和速度会增大。了解影响泥石流路径、速度和尺寸的因素将有助于制定有效的减灾措施。 该项目的重点是为有助于泥石流夹带地表物质的过程建立科学基础。 在更长的时间尺度上，泥石流有助于塑造景观和指导某些矿床的放置，因此记录控制过程有助于更有效地定位和获取矿产资源。此外，土地利用、气候和人类住区的变化模式可能会改变泥石流的规模和频率，因此，了解泥石流的机械行为将有助于更好地模拟和预测泥石流的发生。该项目将使用实验，模拟和现场数据来确定泥石流夹带和沉积的各种机制的重要性，以及随后从颗粒尺度效应到宏观动力学的流动性。研究活动将确定夹带的主要机制，因为它们可能随规模而变化。实验将在明尼苏达大学和维也纳的自然资源和生命科学大学的较小和较大的水槽中进行。水槽装有仪器，以监测孔隙压力和床层应力等细节，高速高分辨率相机将捕捉流动以及床层材料结构和夹带的演变。现场数据将收集在一个仪器化的网站，能够测量力，侵蚀和运动学，如流深。将采用离散元法进行模拟，以帮助解释实验无法获得的动力学。研究结果将纳入一个能够预测大规模泥石流动力学的深度平均连续模型。拟议研究的相关性扩展到自然界和工业中广泛的颗粒流体流动，包括陆上和水下流动，以及许多行业的颗粒处理。教育和推广部分旨在通过以下方式扩大公众对一般颗粒物理学的参与和理解，特别是颗粒物理学的应用：（1）为Fon du Lac部落营地为中学生编写的具有文化敏感性的教育材料，（2）通过明尼苏达科学博物馆的一个在线网站“科学嗡嗡”为公众编写的材料，研究人员和学生将定期发布并回答公众关于研究和相关时事的问题，以及（3）积极让本科生参与研究和推广活动，通过少数民族服务机构和其他地方的导师网络招募代表性不足的群体的学生。

A non-technical description of the project's broader significance and importanceA debris flow is a dynamic moving mass of water, mud, soil and larger objects up to boulder size that is the main ingredient in a landslide. In steep hillslopes and mountainous regions a debris flow can travel over 160 km/hour (100 miles / hour) and can grow to over 20,000 m3 (700,000 cu.ft.), posing significant hazards to human life and infrastructure. Debris flows often begin as relatively small landslides that grow in size and speed as a result of the incorporation or entrainment of surface materials along its path. Knowing what influences the path, speed, and size of a debris flow will contribute toward the development of effective hazard mitigation practices. This project focuses on building a scientific basis for the processes that contribute to entrainment of surface materials by debris flows. Over much longer time scales, debris flows have contributed to shaping the landscape and directing the placement of certain mineral deposits, so documenting the controlling processes can contribute to more efficient location and acquisition of mineral resources. In addition, changing patterns of land use, climate, and human settlement may alter the magnitude and frequency of debris flows, so that knowledge of their mechanistic behavior will enable better modeling and prediction of their occurrence. A technical description of the projectThis project will use experiments, simulations, and field data to determine the importance of various mechanisms in debris flow entrainment and deposition, and the subsequent mobility from particle-scale effects to macroscopic dynamics. The research activities will determine the dominant mechanisms for entrainment as they may vary with scale. Experiments will be performed in smaller and larger flumes at the University of Minnesota and at the University of Natural Resources and Life Sciences in Vienna. The flumes are instrumented to monitor details such as pore pressures and stresses in the bed, and high-speed high-resolution cameras will capture flows as well as the evolution of the structure and entrainment of the bed materials. Field data will be gathered at an instrumented site with capabilities to measure forces, erosion, and kinematics such as the flow depth. Simulations will be performed with Discrete Element Method to help interpret dynamics inaccessible to the experiments. Results will be incorporated into a depth-averaged continuum model capable of predicting large scale debris flow dynamics. The relevance of the proposed research extends to a wide range of particle-fluid flows in nature and industry, including both subaerial and subaqueous flows, and particle processing across many industries. The educational and outreach component seeks to broaden participation and public comprehension of granular physics in general and applications to geophysics in particular through: (1) culturally sensitive educational materials developed for Fon du Lac Tribal camps for middle and high school students, (2) materials developed for the public through Science Buzz, an on-line site of the Minnesota Science Museum, where the investigator and students will post regularly and answer questions of the public about research and related current events and (3) actively involving undergraduates in research and outreach components, recruiting students of underrepresented groups through an established network of mentors at minority serving institutions and elsewhere.