| 摘要 |
PURPOSE:To easily build a steel-made frame which is sectioned in a U shape at a necessary place in a tunnel section and to measure the stress of the bedrock directly and accurately by using the steel-made frame and fitting a flexible tube previously. CONSTITUTION:The flexible tube 4 equipped with a liquid injection port 2 and a pressure gauge connector 3 is put in the cavity part of the steel-made frame 1 which is sectioned in the U shape. Then the frame is built along an excavating surface 7 having its opening part opposite after a tunnel 6 is excavated in the ground 5. A pressure gauge 8 is fitted to the connector 3 of the tube 4 after the frame is built, and liquid such as water is pressurized and injected into the tube 4 from the injection port 2, so that the tube 4 pressed against the excavating surface 7. A cock provided to the injection port 2 is closed after the internal pressure of the tube 4 reaches specific pressure large enough for contacting with the excavating surface, and thus measure ment preparations are completed. Then, the expansion pressure of the bedrock that the tube 4 contacts is measured by the pressure gauge 8 through the intervention of variation in the hydraulic pressure in the tube 4. Thus, the stress of the bedrock is measured accurately.
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