PROBLEM TO BE SOLVED: To provide a pore water pressure meter for accurately measuring pore water pressure for a long term in an unsaturated ground while preventing air from getting mixed therein. SOLUTION: This pore water pressure meter comprises a container 10 having an inflow port (opening 12) for pore water only in its upper part, a water-permeable filter 30 for closing the inflow port (opening 12), and a pressure sensor 20 having a sensitive part 21 within the container 10 for measuring pore water pressure. Since the container 10 has the inflow port 12 only in its upper part, water in the container 10 is not drained off but penetrates in the gravitational direction, making it possible to prevent air from getting mixed in the container 10. Accordingly, pore water pressure can be accurately measured for a long term. Further, since the inflow port 12 for pore water is closed by the filter 30, it is possible to measure only the water pressure of pore water having filtered through the filter 30 to penetrate into the interior of the container 10. COPYRIGHT: (C)2006,JPO&NCIPI

Pore water pressure meter

PROBLEM TO BE SOLVED: To provide a high resolution water pressure measuring device suitable to measure the penetration depth of a probe for a cone penetration test to underwater ground of a large water depth region with high accuracy, a depth measuring device, and a penetration probe.SOLUTION: A device 100 for measuring water pressure has a differential pressure gauge 16 composed of a high pressure side introduction part 12 and a low pressure side introduction part 14 to measure differential pressure between water pressure introduced by the high pressure side introduction part 12 and water pressure introduced by the low pressure side introduction part 14, a water pressure chamber 18 that can introduce water pressure to be reference in the underwater, and an on-off valve 22 for opening and closing communication between the water pressure chamber 18 and the outside, and the low pressure side introduction part 14 introduces the pressure of the water pressure chamber 18.

Water pressure measuring device, depth measuring device, and penetration probe

PURPOSE:To improve the very weak underground dynamic pore water pressure measuring accuracy of a pressure transducer by eliminating the influence of the magnitude of a hydrostatic pressure caused by the depth of water or earth pressure on the measurement CONSTITUTION:The peripheral edge section of a discoid strain starting section 1 is united to the internal surface of a main body section 2 Pressure receiving plates 4 and 4 are respectively fitted to both ends of a pressure receiving rod 3 fixed at the center of the section 1 Strain gauges 6 are fitted to the section 1 Bellows 5 and 5 are respectively fitted between the plates 4 and 4 and section 2 in airtight state and hollow chambers are formed in the bellows 5 and 5 Filters 9 and 10 having different mesh sizes, namely, different attenuation characteristics are provided around the plates 4 and 4 When this transducer is buried in the sea bottom, the hydrostatic pressure generated by the depth of water acts on the plates 4 and 4 through the two filters 9 and 10 and offset each other, but a dynamic pore water pressure having a high frequency passes through the filter 9 having the rough mesh size and acts on the plate 4 Therefore, only the dynamic pore water pressure can be detected with the strain gauge 6

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Papers

Electric pressure transducer

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Papers

Electric pressure transducer

興一矢部