Development of a Ring-Shear Device for Study of Subglacial Processes

该奖项支持环剪装置的开发，用于研究影响冰团地貌效应和动力学的各种滑动驱动过程。该项目的智力价值在于，它将提供一个受控的实验室环境，用于研究自然界中难以观察到的现象。该装置的特点将包括使用刚性或沉积物床，无限滑动位移，控制剪切应力或滑动速率，向滑动方向垂直的冰的不受抑制的运动，控制基础水压，温度控制到0.01℃，以及连续观察床上的滑动，沉积物运动和空洞生长。来自爱荷华州立大学以外的团体将被鼓励使用该设备来研究特定的冰下过程，包括但不限于基于基础水压的湿基冰川滑动、沉积-直至沉积、与基础冻结相关的取水强化、岩石和沉积物床的侵蚀、极地冰川的滑动和沉积物夹带、充满碎屑的冰在岩石上的滑动、冰下直至变形和耕作。仅要求对设备的设计、建造和测试提供支持。这个项目更广泛的影响是，这个装置将为研究冰下过程提供一个新的研究工具。其他对冰川沉积或类似于冰川下发生的过程感兴趣的地球科学家也可能从中受益。例如，岩土工程师（岩土的应力/应变史）、地球物理学家（断层力学）和冻土科学家（冻胀力学）。新的多功能设备将取代现有的用于培训学生的系统。该设备将为学生提供更广泛的研究机会，并通过直接观察冰川下的过程来加强课堂教学。此外，该装置将被用作向公众宣传的工具，就像在挪威恩格布雷恩冰川下进行的实验一样。

This award supports the development of a ring-shear device for the study of a wide range of sliding-driven processes that influence the geomorphic effects and dynamics of ice masses. The intellectual merit of the project is that it will provide a controlled laboratory environment in which to study phenomenon which are difficult to observe in nature. The features of the device will include use of a rigid or sediment bed, unlimited sliding displacement, control of either shear stresses or sliding rates, uninhibited movement of ice normal to the sliding direction, control of basal water pressure, temperature control to 0.01 C, and continuous observation of sliding, sediment movement and cavity growth at the bed. Groups from outside Iowa State University will be encouraged to use the device to study specific sub-glacial processes which include but are not limited to sliding of wet-based glaciers as a function of basal water pressure, lodgment-till deposition, till strengthening by water withdrawal associated with basal freezing, erosion of rock and sediment beds, sliding and sediment entrainment by polar glaciers, sliding of debris-laden ice over rock, and sub-glacial till deformation and plowing. Support is requested for only design, construction, and testing of the device. The broader impacts of this project are that this device will provide a new research tool for study of sub-glacial processes. Other geoscientists with interests in glacial sedimentation or processes similar to those that occur sub-glacially might also benefit. Examples include geotechnical engineers (stress/strain history of tills), geophysicists (fault mechanics), and permafrost scientists (frost-heave mechanics). The new more versatile device will replace an existing system which has been used to train 9 students. This device will provide an even broader range of student research opportunities and will enhance classroom teaching by allowing direct observation of sub-glacial processes. In addition, the device will be used as a vehicle for outreach to the public, as has been done with sub-glacial experiments beneath Engabreen in Norway.