Method and apparatus for controlled pumping of bentonite around a pipe jacked tunnel
OwnerFrank J. Lorenzen, Mark Gutermaninventors
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Abstract
An apparatus and method for selectively injecting a liquid bentonite slurry around an exterior of a tunnel liner segment which is pressed into a tunnel being concurrently excavated during a pipe jacking installation. The bentonite slurry lubricates the exterior of the tunnel liner reducing the force required to press the tunnel liner into the tunnel. The apparatus allows an operator of the pipe jacking operation to selectively inject bentonite around individual tunnel liner segment or to allow the apparatus to selectively inject bentonite as required by a preset injection pressure threshold value.
Claims10
A bentonite distribution system for lubricating a tunnel liner surface with a quantity of bentonite slurry as the tunnel liner is pressed through a tunnel, comprising:
- a tank for holding the bentonite slurry, the tank having a selectively operable mixer mechanism for agitating the bentonite slurry, the tank having an opening for input of a quantity of dry bentonite and an opening with a selectively operable tank valve for input of a quantity of water and an opening with a selectively operable tank valve for output of the agitated bentonite slurry;
- a selectively operable pump for drawing the bentonite slurry from the tank, an input for the pump fixedly attached to the output of the tank, an output of the pump fixedly attached to a conduit extending into the tunnel;
- a selectively operable tunnel valve, the tunnel valve input fixedly attached to the conduit, the tunnel valve disposed on the tunnel liner, an output of the tunnel valve extending through a wall of the tunnel liner discharging the bentonite slurry to an exterior surface of the tunnel liner;
- and
- a control device, the control device inputs fixedly connected to the tank valve and the tunnel valve and the pump and the mixer mechanism, the control device monitoring each input for status, the control device output selectively controlling the tank valve and the tunnel valve and the pump and the mixer mechanism.
A method for lubricating a tunnel liner surface with a quantity of bentonite slurry as the tunnel liner is pressed into a tunnel using a bentonite distribution system, steps comprising:
- mixing the bentonite slurry in a mixing tank until the bentonite slurry achieves a liquid state;
- pumping the liquid bentonite slurry through a conduit into the tunnel;
- dispersing the liquid bentonite slurry to a series of selected tunnel liner segments throughout the length of the tunnel;
- and
- selectively injecting the liquid bentonite slurry through an access in a wall of the tunnel liner segment to the exterior of the tunnel liner.
Dependencies are inferred from the claim text.