| 摘要 |
<p>PROBLEM TO BE SOLVED: To enhance the safety of an existing structure by drilling the floor of the existing structure, arranging a gas collecting pipe having an opening on the side part within the drilled hole, and collecting and draining the gas under the existing structure by the gas collecting pipe. SOLUTION: A floor 12 of an existing structure 10 is drilled by a core cutter, and a broken stone formation such as crushed stone 14 or gravel or a banking is excavated for a hole to bury a gas collecting pipe 20. A suction piping 21 is connected to the gas collecting pipe 20, and underground gas 40 is sucked and drained by a vacuum blower. When the concentration of the underground gas 40 such as methane gas is high, the underground gas 40 is diluted and discharged to prevent the explosion of the gas. Therefore, a diluting piping 22 is connected to the suction piping 21, and a diluting gas 41 such as air is sent to the suction piping 21 and mixed to dilute the underground gas 40. At that time, a flow regulating valve 24 or a flowmeter 25 is mounted on the diluting piping 22 to regulate the flow rate of the diluting gas 41, so that the underground gas is diluted lower than the explosion limit. Thus, the underground gas 40 can be easily drained.</p> |
