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

泥石流是水、泥浆、土壤和大到巨石大小的物体的动态移动体，是滑坡的主要成分。在陡峭的山坡和山区，泥石流的速度可超过160公里/小时(100英里/小时)，并可增长到20,000立方米(700,000立方英尺)以上，对人类生命和基础设施构成重大威胁。泥石流通常以相对较小的滑坡开始，由于沿途表面物质的并入或夹带，滑坡的规模和速度都在增加。了解影响泥石流路径、速度和大小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卷卷地表材料的过程建立科学基础。在更长的时间尺度上，泥石流有助于塑造地貌和指导某些矿藏的放置，因此记录控制过程可以有助于更有效地定位和获取矿产资源。此外，土地利用、气候和人类住区模式的变化可能会改变泥石流的规模和频率，因此对泥石流机理行为的了解将能够更好地对其发生进行建模和预测。该项目的技术描述该项目将使用实验、模拟和现场数据来确定泥石流夹带和沉积中各种机制的重要性，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，因为它们可能随着规模的不同而不同。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更小和更大的水槽中进行。水槽的仪器被用来监测床层中的孔压和应力等细节，高速高分辨率相机将捕捉流动以及床层材料的结构和夹带的演变。现场数据将在仪表化现场收集，具有测量力、侵蚀和运动学(如水流深度)的能力。将使用离散元方法进行模拟，以帮助解释实验无法获得的动力学。结果将被合并到能够预测大规模泥石流动力学的深度平均连续模型中。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，包括水下和水下流动，以及许多行业的颗粒加工。教育和推广部分力求扩大公众对粒子物理学的一般参与和理解，特别是通过以下方式：(1)为丰杜拉克部落营地的初中生和高中生编写对文化敏感的教育材料，(2)通过明尼苏达科学博物馆的在线网站Science Buzz为公众开发材料，研究人员和学生将定期在这里张贴研究和相关时事报告，并回答公众关于研究和相关时事的问题；(3)积极让本科生参与研究和推广部分，通过在少数族裔服务机构和其他地方建立的导师网络，招收代表不足群体的学生。

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.