METHOD FOR PERFORATING A FOREHEAD OF A TUNNEL BOTTOM Russian patent published in 2020 - IPC E21D11/00 E21D9/00 

FIELD: mining.

SUBSTANCE: invention relates to advance anchorage of mine workings from bottomhole space and can be used in construction of deep underground stations in weakly resistant soils, as well as in mining industry and tunnel construction. According to the proposed method, horizontal wells are drilled from the bottomhole space of the tunnel parallel to the tunnel axis through a tunnel shot face shotcrete forehead. Then, fiberglass anchors are installed and cemented in wells. After reinforcing the forehead of the bottomhole of the tunnel, the soil is developed using mechanical means, wherein the fiberglass anchors are cleaved to ensure the integrity of the cemented anchors with a length of not less than 0.6–0.8 of the diameter of the tunnel. Then forehead is made of mined working face with shotcrete. New horizontal wells are drilled through the shotcrete layer parallel to the tunnel axis, wherein new wells are shifted relative to previously drilled wells at a distance of at least three well diameters. As a result of drilling new wells overlap area is formed with minimum length of well overlap zone equal to 0.6 of tunnel diameter. In new wells, fiberglass anchors are installed and cemented.

EFFECT: technical result consists in prevention of development of deformations of rocks in the bottomhole zone of the tunnel, reduced scope of works for drilling of wells for installation of anchors and tunneling time, as well as higher reliability of anchor forehead leading anchor fastening and safety of work in bottomhole during construction of underground deep underground stations by closed method of works.

1 cl, 3 dwg