Difficulties in sinking shafts under balanced head conditions
through hard clay on NORTH WEST WATER LTD's Fylde Coastal Water Improvement
scheme prompted AMEC Tunnelling to contact Bennett Associates to design a
solution.
Overall requirements were established and a brief feasibility
appraisal produced a conceptual design which incorporated new equipment working
in combination with AMEC's existing spoil removal shaft grab arrangements.
An order was placed on Bennett Associates to carry out the
development, detail design and project management of the manufacture of the
complete system.
Following a six week development and detailed design period,
manufacturing was carried out within eight working weeks of order placement on
the suppliers.
The system is designed for use within a 6mm internal diameter
shaft, sinking to a depth of 35m. The hydraulically powered telescopic excavator
assembly, incorporating fixed and rotating supporting rings, allows full
excavation of the shaft bottom extending out to the shaft cutting edge.
The anchorage requirements for the excavator assembly to the shaft
bottom, which not only support the excavator mounting ring but resist the high
bucket break-out forces required for adequate excavation of the clays, are
catered for by a custom designed combined steel and concrete cutting edge
designed by AMEC.
In order to minimise inaccessible hydraulic valve work at the
excavator, the system incorporates individual feeds of each function direct from
the power pack via a hose management system. This is designed around the existing
shaft top set up.
A stand-alone containerised diesel powered hydraulic power pack
provides the motive power with an operator's control cab incorporating all
controls including a positional feedback monitor display of the excavator arm.
The power pack also incorporates hydraulic feeds for operation of the shaft
jacking system.
Currently the excavator has completed two shafts operating
submerged at depths as low as 20m below water level. It is shortly commencing on a
third shaft.
Close collaboration with AMEC allows ongoing development of the
prototype machine and patent rights are being pursued.
For more information, contact us on 01709-373782
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