簡易自動採水器の試作について (その2)-ボーリング孔用深度別採水器-

Abstract

A new type of water sampler was designed for the sampling of groundwater from differentdepths in slender boreholes. It is of cylindrical shape with a diameter slightly smaller than thatof the borehole. When the sampler is going down in a borehole, water comes into it through aball bulb at the lower end and leaves it through a slit near the upper end. The ball bulb is keptopen by a float connected to it due to the bouyancy and the drag force of the flowing water. Butwhen the sampler is going up, the ball bulb is shut by the drag force of water acting in the reversedirection. The float is installed at the upper end of the sampler so that it also control the effectof the slit. The result of the laboratory test is compared with a theoretical solution and then theparameters representing the performance of the sampler was determined. Accordingly, the lengthof the sampling range is 40 cm when the sampler of a diameter of 3 cm is used in a borehole ofa diameter of 3.5 cm, but becomes 95 cm when the diameter of the borehole is 10 cm. It is re-vealed that the contribution of the water 10-15 cm above the maximum depth attained by thesampler is maximum in the sampled water. Discussion is also directed to increased hydrologicalinformation which can be expected when this type of sampler is used.