| Preloading filling spiral casing structure is a widely used structure style in hydropower plant, the gap between steel liner and its surrounding concrete in this structure,is not only in connection with the inner filling pressure, additionally, temperature caused by hydrated heat during concrete pouring and the variation of water temperature and air temperature during working period, could also influence its shape, and effect the safety and durability of the whole structure in the further way.However, the shape of the scroll case is very complex, the thermal property and mechanical property of the materials varies from temperature to temperature, the temperature value and fields of the structure during concrete pouring and working period was not ease to be ascertained, all these factors make it rather difficult to do clear research on this subject, and still no related paper have been published yet. Based on the theories of finite elements method and thermal conduction, and in accordance with the practice of Xilongchi hydropower station in Shanxi province, a study focused on the influence of temperature on the gap between concrete and steel liner during concrete pouring and working period has been carried out in this paper, by using ANSYS software as the main calculate tool.Through simulate the concrete pouring process, the development of the temperature field was calculated, and the influence of temperature caused by hydrated heat on the gap was known. It was indicated that, due to the influence of the temperature and synchronisms of each layer concrete to hydrate and firm, the gap was non-uniform, where the diameter of the section was bigger in scale, the gap was bigger due to the more influence of temperature achieved. The maximum gap of the whole model is 3.10mm, appeared on the upper right with the angle of a degree between 30 and 60 from the horizontal axis in polar coordinate system, as far as sectional model concerned, the maximum was 2.80mm, appeared on the top of the spiral casing.The development of the temperature field and deformation of the structure was also calculated under winter and summer working period, and then, the influence of changing temperature on the gap was analyzed. The result shows that temperature drop in winter makes the steel liner shrink, thus the gap became bigger, and same on the contrary in summer season, moreover, the gap was also not in an uniform shape. To the Xilongchi hydropower plant, the maximum gap enlarged 0.39mm in winter, and reduced by 0.27mm in summer season.According to two different temperature load conditions, finite element calculation has been performed by using whole structural model and sectional model, and the comparison of the results provides a reasonable way in model building for analyzing the influence of temperature on the spiral casing structure. |
