A Study on the Conditions of Ice Arch Formation at Bridge Piers

建在海上或河流上的桥墩受到浮冰运动引起的各种影响。冰塞的形成尤其对这种结构造成严重的问题。由于冰塞的发展，河流的水位线将上升，超过其堤防，由于融化的雪，并最终将洪水。冰塞也可能作为冰力作用在桥墩上，以及对桥梁上部的推力。此外，由于冰塞缩小了河流的面积，并加快了流速，桥墩将在基础上局部冲刷。浮冰在桥墩上成拱是造成冰塞的因素之一。研究浮冰成拱条件对防止冰塞的形成和控制浮冰的运动具有重要意义。本文介绍了桥墩上浮冰运动成拱条件的模型试验结果。在这项研究中报告。此外，还进行了浮冰和桥墩的形状效果实验，验证了实验中使用的不同尺度的效果。

Bridge piers constructed over the sea or over rivers are subjected to various influences caused by the movement of ice floes. The formation of ice jams in particular poses a significant problem to such structures. As a result of the development of an ice jam, a river's water line will rise over its embankment due to thawing snow and will flood eventually. An ice jam might also work on the bridge pier as an ice force as well as a thrust-up force against the upper part of the bridge. In addition, since an ice jam narrows the area of the river and accelerates the current velocity, the bridge pier will be scoured locally at the foundation. The arch formation of ice floes at the bridge foundation is included as one of the factors which lead to the formation of an ice jam.It is important to study conditions of arch formation by ice floes for the purpose of preventing the formation of ice jams as well as controlling ice floe movement by arch formation.The results of model experiments concerning the conditions of arch formation by an ice floe in movement at the bridge pier are reported in this research. We also conducted an experiment on the shape effect of ice floes and bridge piers while verifying effects depending on the difference in scales used in the experiments.