| 摘要 |
PROBLEM TO BE SOLVED: To specify the position of a crack or a fracture zone by boring holes at equal intervals in a hole of a bet rock, inserting a bored tube including a pore water pressure meter in each hole, injection pressurized water, and displaying the measurement result as a distribution chart on a personal computer via a data logger. SOLUTION: A bored tube 1 is formed by drilling holes 2 at equal intervals in a hollow cylinder body having a length longer than the depth of a boring hole 3 and an outside diameter smaller than its inside diameter and internally arranging pore water pressure meters 6 at equal intervals. The bored tube 1 is inserted into the boring hole 3 while frictional resistance due to unevenness and a bend of the hole is reduced by means of a centralizer 5. A water injection port 10 is arranged in the opening part of the boring hole 3 while the other part is sealed by a seal 11, and water is injected at a constant pressure by means of a water pressurizing device 14. After the water pressure and the water flow become a constant state, the measurement result of the pore water pressure meter 6 is inputted into a personal computer 9 via a cable 7 and a data logger 8 so as to be displayed as a distribution chart. Then, water permeability in each pore water pressure meter 6 is grasped for checking the position of a crack 13 or a fracture zone.
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