The Technical Principle of Self drilling anchor
Self drilling anchor uses hollow anchor bar with thread on surface and one-off drill bit to drill holes and be inserted into stratum by drilling machine. Grouting slurry to stratum makes external of anchor bar wrapping with cement mortar or neat cement paste, which forms combination with surrounding soil and has integral function.
Under the condition of deformation, self drilling anchor forms friction force by contacting with soil body, it restrains and reinforces surrounding rocks and then makes stable.
Self drilling anchor has special elongation function, which can not only protect self drilling anchor, but also control deformation of roadway and benefit stable development of surrounding rocks.
The diameter of borehole has proportional relation with ground stress, inverse relation with cohesive force of coal bed and little relation with frictional angle of surrounding rocks.
The technical process of self drilling anchor is as following: excavating working face, spraying concrete first, positioning self drilling anchor and drill machine, drilling, grouting, spraying concrete pavement, locking self drilling anchor, excavating next stratum.