| 摘要 |
PURPOSE: A relaxed type blasting method and a blast mat structure are provided to reduce noise and vibration caused by a blasting and allow a portion of a free surface of a rock mass layer to be relaxed from a parent rock without affecting public facility such as a transmission tower. CONSTITUTION: A method comprises a first step of dividing a blast section onto a horizontal surface between a free surface and a cut surface of a rock mass layer in a lengthwise direction of the rock mass layer to be excavated, and penetrating a plurality of blast holes having a predetermined spacing for each of the divided portion of the blast section, a second step of connecting a blast wire in such a manner that the explosives inserted into the blast holes of each blast section can be exploded in a predetermined order, a third step of installing a blast mat having an iron plate with a size enough to cover all of the blast holes, the iron plate having at a bottom surface thereof a resilient member surrounding the blast holes, the blast mat having at an upper surface thereof a weight compensating member welded thereto, and a fourth step of exploding the explosives by operating a blasting machine.
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