Design Method for Snow Removal System in an Open Channel Flow using Booster Pump

为了推广明渠除雪系统，应开发各种技术。以下是本研究的结果。从理论和实验两个方面研究了雪在直槽中输送的临界条件。导出了明渠中雪的输移率的新公式。该理论假定水和雪的混合物为宾汉流体，并根据速度分布推导出水深增加率的输移率。用塑料球代替雪进行了模型试验。结果表明，理论可以近似解释雪和水混合物的速度分布。利用模型试验结果对积雪输移率和水深增加率的计算公式进行了验证。进行了现场试验，对增压泵的性能进行了测试。根据积雪输送速率，对泵的效率进行了检验。从而提高了增压泵在排水量不足、河床坡度平缓的情况下的输雪率。设计了缓坡地形下降雪严重的典型城区--长冈市的除雪系统。在设计该系统时，考虑了缓坡渠道的积雪输移率和水深增加率。此外，还考虑了利用增压泵提高积雪输送速率的问题。指出了明渠除雪系统设计中的几个问题。

In order to popularize the snow removal system using an open channel, the various technologies should be developed. The followings are the results of this study.1. The theoretical and experimental studies are carried out to investigate the critical conditions of the snow transport in a straight channel.2. The new formulae of the transport rate of snow floating in an open channel are derived. The theory uses the assumption that the mixture of water and snow is the Bingham fluid, and the transport rate of the increase rate of water depth is derived from the velocity distribuyion.3. Model experiments using plastic balls instead of snow are carried out. It is shown that the velocity distribution of the mixture of snow and water is approximately explained by the theory. Also, the formulae of the snow transport rate and the increase rate of water depth are examined by results of the model experiments.4. The field experiment is carried out to test the performance of the booster pump. The efficiency of the pump are examined for the snow transport rate. As a result, the booster pump is improved as to the snow transport rate under the conditions that the water discharge is not enough and the bed slope is mild.5. The snow removal system in Nagaoka City, which is the typical city area of severe snowfalls under mild slope topographies, is designed. In order to design the system, the snow transport rate and the increase rate of the water depth in a mild slope channel are taken into consideration. The improvement of the snow transport rate by the booster pump is also considered. Several problems for the design of the snow removal system in an open channel are pointed out in this study.