| 摘要 |
PURPOSE:To realize the size reduction of the observation hole as well as the repetitive measurement there by installing the neutron moisture meter into the ground to measure the dilution of the implanted tracer. CONSTITUTION:The observation hole is drilled at fixed measuring ground 12, and filter pipe 13 is installed at the hole. Then neutron moisture meter 1 is implanted down to the observation position within pipe 13. Tracer T is pressed in and exhausted through spillway 8 to be then injected into peripheral ground 12. In this case, the nuclide featuring a large heat neutron absorption cross-sectional area is used for the tracer. Thus the tracer density of the tracer implanted into ground 12 or the area near meter 1 is reduced according to the flow of ground water W. The dilution state of the density is measured by meter 1 and scaler 16, and the flow speed of the ground water is obtained from the reference dilution based on the calibration curve obtained previously and the dilution measured. The calibration curve is produced previously according to the gap rate of the ground. As for measurement of the flow direction of the ground water, meter 1 is turned round the axle to obtan the maximum dilution direction of the tracer and thus to obtain the flow direction of the ground water. |
