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Full-scale avalanche experiments at Ryggfonn, Norway and studies on the dynamics of powder-snow avalanches

挪威 Ryggfonn 的全尺寸雪崩实验和粉雪雪崩动力学研究

基本信息

批准号：
02044005
负责人：
MAENO Norikazu
金额：
$ 5.5万
依托单位：
Institute of Low Temperature Science, Hokkaido University
依托单位国家：
日本
项目类别：
Grant-in-Aid for international Scientific Research
财政年份：
1990
资助国家：
日本
起止时间：
1990 至 1991
项目状态：
已结题

项目摘要

Among two types of snow avalanches the release and dynamic characteristics of wet snow avalanches are rather simple, but those of dry snow avalanches, especially of powder-snow avalanches, are complex and more detailed information is required. The present study was initiated in aiming to make various observations about internal structures and dynamic properties of powder-snow avalanches.Natural snow avalanches were observed at Shiai-dani in Kurobe Canyon by taking video-films and installing various sensors including impact pressure sensors and ultrasonic anemometer. One of the findings was the record of avalanche winds detected by a ultrasonic anemometer. The avalanche wind was observed to precede the avalanche body.Snow avalanches were artificially released at Ryggfon site in Norway. So far three avalanches were observed ; in one avalanche the mean running speed was 22 m/s, the volume and maximum depth of the debris were 20, 000 m^3 and 5 m respectively. The observation of size distribution of the constituent snow blocks showed that the larger ones tended to be accumulated at the front part of avalanches.Laboratory experiments of snow avalanches were also carried out by flowing numerous ice spheres (diameter 2.9 mm) in a 5-m long chute at temperatures from 0 to -30ﾟC. Measurements of velocities and densities of ice spheres showed significant inhomogeneity in the internal structure vertically as well as horizontally.

在两种类型的雪崩中，湿雪崩的释放和动力学特性比较简单，而干雪崩，特别是粉雪崩的释放和动力学特性比较复杂，需要更详细的资料。本研究的目的是对粉末雪崩的内部结构和动力学特性进行各种观测，通过拍摄录像和安装各种传感器（包括冲击压力传感器和超声波风速计），对黑部峡谷的Shiai-dani自然雪崩进行了观测。其中一项发现是超声波风速计探测到的雪崩风记录。在挪威的Ryggfon现场，雪崩风先于雪崩体被观测到。到目前为止，共观测到三次雪崩;其中一次雪崩的平均移动速度为22 m/s，碎片的体积和最大深度分别为20，000 m^3和5 m。对组成雪块的大小分布的观察表明，较大的雪块往往堆积在雪崩的前部.在实验室中，我们还进行了雪崩的实验，在0 ~-30 ℃的温度下，在一个5米长的斜槽中流动许多冰球（直径2.9毫米）.对冰球速度和密度的测量表明，冰球内部结构在垂直和水平方向上都存在显著的不均匀性。