080731 6LYG A1 Particular Tunnelling Specification ... - SCATnow

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Lee Tunnel, Contract No. 6LYG/A1 PT – Particular Tunnelling Specification - PT200 Contractor shall nominate a recognised main bearing supplier and possible delivery time mitigation to meet TBM delivery requirements. PT213.5 Main drive gearboxes and motors shall have a rating of not less than 10,000 hours B10 life for the given load cases selected for the main bearing by the Contractor. PT213.6 PT213.7 PT213.8 To mitigate any risk of gearbox or drive pinion failure causing damage to the main bearing gear final drive pinions meshing with the main gear shall have bearing supports on each side of the pinion to remove bending moments. The Contractor shall submit the details of the gearbox drive pinions and support bearings to the Project Manager. Sampling points shall be provided for all lubricants in accessible points. TBM drive system shall be bi-directional. PT214 PT214.1 PT214.2 PT214.3 PT214.4 PT214.5 PT214.6 PT214.7 PT214.8 PT214.9 EXCAVATED MATERIAL MUCKING SYSTEM If proposing an EPBM, fit and operate earth pressure balance tunnel boring machine with a screw conveyor in closed mode or in open mode to remove excavated material from the cutterhead chamber. Design the screw conveyor for operation in abrasive soil and for efficient replacement from within the tunnel. If proposing an EPBM, the screw conveyor shall be designed to maintain the required face pressure within the cutterhead chamber and the entrance to the screw conveyor. Pressure shall be reduced to atmospheric at the screw exit by control of the screw conveyor. The tunnel boring machine shall be capable of controlling face pressure to within ± 0.3Bar of the hydrostatic pressure. If proposing an EPBM, design the screw conveyor to be capable of being closed and sealed against earth pressure at each end. The front of screw conveyor shall be located at the base of the pressure chamber and shall project into chamber when operating. The screw shall be capable of being withdrawn in order to close front bulkhead door for maintenance and removal of obstructions. The design of the discharge shall include a system of flow dividers to prevent jamming. In the event of a power failure the discharge gate shall be closed by a stored power system. Fix the exit/outlet end of the EPBM screw conveyor with a pressure lock-out device to separate the pressurized ground water and muck from atmospheric pressure. For EPBM, provide mixing arms within the muck chamber to uniformly condition the material in the chamber. If proposing an EPBM provide and calibrate, as a minimum, six pressure cells in the mucking chamber and a minimum of four pressure cells on the screw conveyor all as recommended by manufacturer or as needed to assure accuracy of pressure measurements. Both EPBM and SPBM shall utilise the pressure gauges to detect water inflow into the mixing chamber to establish prevailing ground permeability. If proposing an SPBM provide a minimum of four agitator paddles in the suction zone of the Working chamber. The slurry circuit shall be designed to handle a minimum of: a) Solids volume per hour 300 cum. b) Total weight of solids volume removed 600 t/hour. c) Minimum slurry velocities of 4 m/s to ensure solids remain in suspension. The slurry system shall be equipped with: a) A means of measuring discharge slurry densities and velocities. Thames Water Utilities Limited August 2008 Page 10 of 38
Lee Tunnel, Contract No. 6LYG/A1 PT – Particular Tunnelling Specification - PT200 b) A system which measures the excavated spoil mass and compares with the theoretical mass per ring of excavation, to prevent over excavation. c) A charge and discharge slurry pipe extension system including the necessary pipe handling machines. d) Non-return valve system to prevent slurry spillage into the tunnel when extending the pipes. e) Electrical programmable pump controllers to regulate and maintain the slurry circuit pressure. f) Bypass circuit and re-circulating controls. g) The Contractor shall design the slurry system to cater for anticipated spoil including the high strength flints, cobbles and associated abrasive materials. h) The Contractor shall carry out a risk assessment based on previous experience of similar systems in similar ground conditions to determine the location and which components will be subject to high wear and maintenance. i) The Contractor shall design the slurry main system to facilitate planned removal of high wear components with minimum down time. j) The Contractor shall have available appropriate spares for replacement of components including pumps and pipes. k) The Contractor shall prepare and submit his planned maintenance manual to the Project Manager. l) The Contractor shall provide the design of the proposed Rock Crusher to the Project Manager which shall then be tested with samples of flint to demonstrate its capability to crush them. m) A proven design of rock crusher or crushers shall be provided to reduce flint rock to a size of 100mm. The crusher or crushers shall be serviced from the rear face of the forward bulkhead in free air conditions. They shall form part of the slurry discharge system to ensure that all large rock pieces are reduced in size. The rock crushers shall be capable of crushing rocks (flints) as described in Contract Documents. The crusher or crushers shall be sized on an excavation solids volume of 300 cum/hour of which it can be expected 75cum/hour may consist of flint pieces. n) For SPBM, the TBM shall be designed to work under all conditions described in the Works Information and Site Information. This includes the complete slurry system required to stabilize the face and drive the tunnel. The slurry machine shall be capable of controlling the applied face pressure to within 0.3Bar of the hydrostatic head. o) If proposing SPBM the contractor shall provide a high pressure flushing system with the capability to direct flows to improve the agitation of the slurry and break up blockages in the area of the aperture of the submerged wall and in the area of the entrance to the suction pipes. p) If proposing a SPBM the TBM shall be capable of supporting hydrostatic pressures of up to 8Bar with an equivalent or greater slurry pressure q) Use a conveyor, rail or slurry system for muck transport in the tunnel. Design the system for the materials stated in the GBR, including abrasive flint chards, chalk fines and Thanet Sands. All proposed systems shall take into consideration the designed gradients of the tunnel and the safety of the underground personnel. r) For all conveyor belt systems, there shall be an audible alarm with a red flashing warning light giving the operatives advanced warning that the conveyor belt is about to start moving. Emergency stop buttons shall be Thames Water Utilities Limited August 2008 Page 11 of 38
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080731 6LYG A1 Particular Tunnelling Specification ... - SCATnow

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