The Robbins Company

Peter B Dowden

David T Cass

David B Sugden

Richard J Robbins

Nicholas A Hynd

A tunneling machine convertible between a 'closed mode' and an 'open mode' of operation, having a rotatable cutterhead with muck openings communicating with a pressurizable cutterhead chamber and a pressure maintenance system to stabilize the tunnel workface when operating in the 'closed mode'. In the 'closed mode' low slurry flow is employed as a liquid pressure balance solely to support the unstable tunnel face. Low slurry flow is supplied through a pressure bulkhead sealing the cutterhead chamber and pressurized conveyor means through the bulkhead removes tunneled material from the cutterhead chamber. A pressure lock connected to the pressurized conveyor means transfers tunneled material to dewatering and reservoir/accumulator means operated at substantially atmospheric pressure. Slurry, with at least most of the solids removed, is recycled to the slurry inlet at a controlled low flow rate matching the rate of removal of tunneled material and slurry from the tunnel face so the otherwise unstable tunnel face is maintained stable. In the 'open mode' of operation, for use in boring a self-stabilizing tunnel face, the pressure bulkhead is removed and a second conveyor, such as a belt conveyor, is disposed adjacent to the 'closed mode' conveyor to withdraw cuttings from the cutterhead chamber.

Tunneling machine having liquid balance low flow slurry system

A shaft boring machine including a rotatable cutterwheel assembly with a horizontal axis mounted on a carriage having vertical travel. The carriage is mounted on a slewing base frame and rotates about the vertical axis of the machine. An excavating unit for muck removal is mounted opposite the cutterwheel on the slewing base frame and loads directly from the shaft bottom into a muck hopper. When the hopper is full, it is discharged into a hoist bucket which is hoisted to the surface. The machine is positioned in the shaft by upper and lower gripper systems. Walking cylinders between the two gripper rings advance the machine up or down the shaft. A method of boring vertical shafts in medium and hard rock which includes the steps of: (a) providing, radially of the shaft, a cutterwheel assembly for cutting the rock; (b) while rotating the cutterwheel assembly about its horizontal axis, plunging the rotating cutterwheel downwardly into the rock; (c) slewing the rotating cutterwheel assembly around the rock work face and about the central vertical axis of the shaft; and, (d) removing the rock cuttings from the work face.

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Kirkland, WA, United States of America

Peter B Dowden