Research on Geothermal Snow Melting using Foundation Piles applied to Bridges

开发了利用基桩模拟地热融雪系统的模拟软件。融雪模型建立在融雪路面、桩、土、消雪管等之间的热能平衡基础上，可以模拟路面积雪、积雪、土壤中的热能储存等情况，也适用于多桩成格状布置的系统，如桥梁基础桩等。为了模拟路面融雪，还考虑了积雪层内的温度分布，使其适用于东北、北海道等高寒地区的积雪融化情况。软件的输入数据包括：集热桩和蓄热桩的尺寸和布置、土壤的组成、路面的尺寸和结构、散热管的尺寸和布置、种类和…软件输出的数据包括路面融雪情况、路面积雪和积雪情况、桩内热媒平均温度、路面平均温度、换热量、循环泵运行时间等。该融雪系统在中津路人行天桥、福井市研究中心内路面和札幌市试验路面进行了现场测试。模拟结果与现场试验结果吻合较好，表明了本研究开发的模拟软件的有效性。此外，模拟还证明了采用适当间距的多个桩进行季节蓄热的可能性，夏季土壤中储存的热量不会散失太多，从而可以用于冬季的融雪作业。这种季节蓄热得到了实验验证，并用于在建的新清永大桥的设计。较少

Simulation software was developed for simulating geothermal snow melting system using foundation piles. The snow-melting model is based on thermal energy balance among snow-melting pavement road surface, piles, soil, dissipation pipes and etc. The software can simulate situations of melting snow and remaining snow on road surface, storage of thermal energy into soil, and etc. It is also applicable to the system with multiple piles, where the many piles are arranged in lattice configuration such as foundation piles of bridges. For simulating snow melting on road surface, temperature distribution inside snow layer is also considered so that the software can apply to snow melting situations for frigid regions such as Tohoku and Hokkaido district.Input data for the software are as follows : dimensions and arrangement of heat collecting and heat storage piles, constitution of soil, dimensions and structure of pavement road surface, dimensions and arrangement of dissipation pipes, kinds and … More flow rate of heat medium, meteorological data such as rainfall including snowfall, air temperature, wind velocity, humidity, solar radiation, sky radiation and etc. Output data from the software are as follows : situations of melting snow and remaining snow on pavement road surface, mean temperature of heat medium inside piles, mean temperature of pavement road surface, transferred heat, operation time of circulation pump, and etc.Field tests of this snow-melting system have been conducted at Nakamaizuru pedestrian bridge, road surface inside Research Center in Fukui city and test road surface in Sapporo. The simulation results are in good agreements with these field tests results, that show validity of the simulation software developed in this research.In addition, the simulation demonstrated possibility of thermal storage during seasons using multiple piles with appropriate pitch, where stored heat inside soil in summer does not dissipate so much that the heat can be applied to snow-melting operation in winter. This thermal storage during seasons was experimentally confirmed and utilized to design of Shin-Kiyonaga bridge under construction. Less