Application of Double-pipe Pressure Grouting Technology in Gas Pressure Measurement

A technique of gas pressure measurement with hole sealing by use of double-pipe pressure grouting technology and M-Ⅱ gas pressure detector was proposed for coal seam with high pressure water in roof or floor and fracture development. The technique uses casing pipe to avoid influence of hole wall collapse of surrounding rock, uses high-pressure grouting to fill surrounding rock cracks and cut off leak channels of gas, and uses M-Ⅱ gas pressure detector to measure gas pressure accurately and reliably. The test result of gas pressure measured with the technique showed that the technique completely fills wall rock cracks and water bearing channels, which makes drilling hole for pressure measuring more firmly and stably, removes interference of pressure water on pressure measurement, relieves restriction for pressure grouting because of drilling collapse, so gas pressure can be measured accurately.