| 摘要 |
PROBLEM TO BE SOLVED: To elongate the length to be inspected at one time and make it possible to precisely judge the defect part due to the application of a load to a joint by a method wherein an air-permeable flexible hollow cord is provided between the overlapped parts of water-impervious sheets at a joint to the longitudinal direction of the joint so as to evacuate the hollow cord in order to detect the change of the pressure in the cord. SOLUTION: Joining layers 5 and 6 having an interval between each other are arranged between the overlapped parts of the end part of and upside impervious sheet 2 and of that of a downside impervious sheet 3 so as to turn a space surrounded by the upside and downside impervious sheets 2 and 3 and the joining layers 5 and 6 into an airtight passage 4. In the passage 4, an airpermeable flexible hollow cord 8 is interposed freely and movably. Prepared unshaped sealing materials 14 are filled between the joining layers 5 and 6. The inserting pipe 11 of a vacuum pump 10 is inserted in the hollow cord 8 at its end part. The interior of the hollow cord 8 is evacuated so as to read the pressure under a pressure-reduced state in the cord wit a pressure gauge 13 after the elapse of a predetermined period of time. If the change in pressure is indicated, the existence of the defective joining part in the section, in which the inserting pipe is inserted, is revealed. |
