Abstract: The head is carried by two flexible continuous drill pipes which surround each other and which are flexible enought to be uncoiled from a reel but which are still rigid enough almost not to get twisted in the ground on themselves or relative to each other during the operation of the head. The head is directed in the ground by means of fluid wich is pumped through one of the pipes and wherewith the head is repelled relative to the wall of the already formed portion of the hole. One of the pipes connects to one or more directable spray nozzles on the front end of the head, the other one connects to one or more sidewise-issueing openings wherein preferably a directable spray nozzle is mounted.

Abstract: The head is carried by two flexible continuous drill pipes which surround each other and which are flexible enough to be uncoiled from a reel but which are still rigid enough almost not to get twisted in the ground on themselves or relative to each other during the operation of the head. The head is directed in the ground by means of fluid which is pumped through one of the pipes and wherewith the head is repelled relative to the wall of the already formed portion of the hole. One of the pipes connects to one or more directable spray nozzles on the front end of the head, the other one connects to one or more sidewise-issueing openings wherein preferably a directable spray nozzle is mounted.

Abstract: The invention provides apparatus for making a tunnel. A flexible tube connects to a head consisting of a body and a nose mounted for movement thereon. The nose has an abutment face adjustable in position relative to said body, and carries a nozzle. The nose may be a bevelled cylinder which may be rotatable relatively to the body by a steering mechanism or be conical and be tiltable by jacks operable from above the ground.