The invention discloses a method for measuring
gas pressure of a
coal seam by a casing high-pressure hole sealing method. The method comprises the following steps: a, a hole is opened with a large-
diameter drill bit, the depth of a casing can be increased by drilling, and then the casing with a
flange at the outer end is sent into the hole; b,
expansive cement mortar is injected into the hole in a grouting mode to enhance the casing; c, after the
expansive cement mortar is solidified, drilling is carried out with a
drill bit which is one size smaller than the large-
diameter drill bit in step a along the original drilling center, the drilling is stopped when a
coal seam is approached, and the
expansive cement mortar is injected into a whole-hole section in a grouting mode for reinforcement after drilling cuttings are removed; d, after the expansive
cement mortar is solidified, the hole is drilled with a
drill bit which is one size smaller than the
drill bit in step c along the original drilling center until the
coal seam is penetrated; and e, the
flange at the outer end of the casing is connected with a pressure gage to measure
gas pressure. Large and small gaps and gap water around the
drill hole can be effectively blocked in a high-
pressure grouting method, an
air leak channel is sealed, and rapid and accurate
pressure measurement is realized.