X-Ray Photography Method for Experimental Studies of the Frozen FringeCharacteristics of Freezing Soil

摘要

The main objectives of this report are: (1) To describe the development of an X-ray photographic method for observing the frost-heaving properties of soil, especially the characteristics of the frozen fringe; (2) To describe observations of the temperature and strain field change in the frozen fringe using the procedure developed; and (3) To publish the test results as a data base that can be used in evaluating frost heave models. The method used X-ray photography with thermocouples installed inside lead marking spheres to observe soil expansion, including expansion due to in-situ freezing and expansion due to segregation freezing. The method includes an image-processing technique for analyzing the coordinates of the lead spheres on the photos, a three-dimensional analysis of the lead spheres' coordinates to compensate for the geometrical distortion caused by the use of a point X-ray source, and direct measurements of the temperature at each lead sphere using thermocouples in the spheres. Therefore, both the deformation and the temperature field in a freezing soil can be observed directly. Results on the following characteristics include: Temperature profiles in two freezing soil specimens; The expansion activity (strain and strain rate) distributions in two specimens; The apparent temperature range of the frozen fringe; The apparent thickness of the frozen fringe; and The thermal conductivity of the frozen fringe while the warmest ice lens is segregating. (edc)