Apparatus for in situ lining of an upwardly open shaft with monolithic concrete

Claim 1

Slipform apparatus for lining in situ an elongated upright open vertical walled shaft having a substantially circular cross section extending from a shaft bottom to an open top, said slipform apparatus comprising: an outer slipform member having a conical shape extending downward and radially outward from an open apex to a peripheral edge adjacent the vertical wall of the shaft; an inner core slipform member mounted in coaxial spaced relation to the outer conical slipform member; said inner core slipform member having (1) a conical upper portion coaxial with and spaced from the outer conical slipform member forming a conical passageway extending between the open apex downward and radially outward to the peripheral edge of the outer slipform member and (2) a depending lower cylindrical wall portion to form a cylindrical space between the wall portion and the shaft wall; an elongated tremie tube means connected to the outer slipform member with a lower end in open communication with the open apex of the outer slipform member for directing concrete in a plastic state down the tremie tube through the open apex and through the conical passageway and into the cylindrical space between the cylindrical wall portion and the shaft wall to form the shaft lining; seal means on the outer slipform member at the peripheral edge for preventing the escape of concrete from the cylindrical space to above the outer slipform member; and concrete pressure supply means operatively connected to the tremie tube means for pumping concrete under sufficient pressure through the tremie tube means and the conical passageway to the cylindrical space between the cylindrical wall portion and the shaft wall to force the slipform apparatus upward within the shaft as the concrete is pumped through the tremie tube.