A great quantity of groundwater flows out of the Abo tunnel which passes through the high mountain areas between Gifu and Nagano Prefectures.
A plan which utilizes the groundwater to melt snow on a connecting road to the tunnel is under consideration.
Efficiency of the snow-melting system for road is affected by many factors such as air tempera ture, wind velocity, weather, velocity of snowfall, temperature of the groundwater, depth of the embedded pipe, diameter of the pipe, interval of the pipes, thermal properties of the pipe, flow rate of the groundwater and thermal properties of the road bed, etc. ...
To obtain an optimum snow-melting system utilizing groundwater, the effects of the above factors are discussed separately and synthetically. Using the theoretical studies, a short experimental road, 22m in length and 4.5m in width, was constructed. It included the parallel-pipes system and the hairpin bend pipes system. On and around the road, many sensors were set up to measure the thermal factors for each experimental condition.
Some of the important results are as follows:
1) Optimum interval was 20cm for pipe of 2.5cm in diameter embedded by 7cm in depth.
2) Flow rate of groundwater, 12°C at inlet, necessary to melt the snow is 0.45m
3 hr
-1 per pipe.
3) Temperature of the groundwater flowing through the pipe falls exponentially.
4) Temperature of the groundwater flowing through the embedded pipe should be maintained above 2°C at outlet to melt the snow on the road.
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