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

该奖项支持开发环切变装置，用于研究影响冰块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，在其中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淀层，无限制的滑动位移，控制剪应力或滑动速率，垂直于滑动方向的冰的不受限制的移动，控制基本水压，温度控制在0.01摄氏度，以及连续观察滑动，泥沙运动和床面空洞的增长。来自爱荷华州立大学以外的研究小组将被鼓励使用该装置研究特定的冰下过程，包括但不限于以湿冰川为基础的冰川作为基础水压的函数的滑动、下沉-直到沉积，直到由于与基础冻结有关的抽水、岩石和沉积物床面的侵蚀、极地冰川的滑动和泥沙夹带、富含碎屑的冰在岩石上的滑动以及冰下直至变形和耕作而加强。仅对设备的设计、建造和测试提供支持。该项目的更广泛影响是，该装置将为研究次冰川过程提供一个新的研究工具。其他对冰川沉积或与次冰川类似的过程感兴趣的地球科学家也可能受益。例子包括岩土工程师(耕作的应力/应变史)、地球物理学家(断层力学)和永久冻土科学家(冻胀力学)。新的更多功能的设备将取代现有的系统，该系统曾用于培训9000名学生。这种设备将为学生提供更广泛的研究机会，并通过允许直接观察冰下过程来加强课堂教学。此外，该装置将被用作接触公众的工具，就像挪威恩格布林下的冰下实验所做的那样。

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.