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

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Lee Tunnel, Contract No. 6LYG/A1 PT – Particular Tunnelling Specification - PT200 PT205.8 PT205.9 Diameter of excavated tunnel: to be a minimum of 7200mm ID to match the Contractor’s design and to produce minimal over-excavation and least necessary clearance. Take into account horizontal and vertical grades to be negotiated. Equip TBM with integrated safety systems in accordance with applicable regulatory requirements for underground construction equipment and in accordance with BS6164 2001 “Safety in Tunnelling in the Construction Industry”. PT205.10 All soil conditioning materials, oils, greases, sealing compounds and any other material injected into or in contact with the soil, rock or ground water which is used during the mining operation shall be compliant with all relevant regulatory agencies and the requirements of the Works Information. PT206 PT206.1 PT206.2 PT206.3 PT207 PT207.1 PT207.2 PT208 PT208.1 PT208.2 MINIMUM REQUIREMENTS FOR TBM TUNNELLING EQUIPMENT With particular reference to the Works Information and Site Information, the requirements as detailed in this Section will not modify or detract in any way whatsoever from the Contractor’s sole responsibility for the selection, design and operation of the tunnelling plant and equipment. The Contractor shall supply, assemble, maintain, operate and remove all tunnelling equipment necessary to construct and complete the tunnel in accordance with the Works Information and the ground conditions encountered. Ground Settlement: - The operation and control features of the TBM shall be designed to minimise sub-surface and ground level settlement. Ground loss from the TBM boring and tunnel construction shall be limited to a maximum of 1% of the excavated volume. The Contractor shall demonstrate in the form of a Method Statement the TBM operating principles that shall govern the use of the TBM in order to meet these requirements. The Contractor shall design the TBM to allow for the replacement of the main bearing, rearwards, from within the TBM. FINITE ELEMENT (F.E.) ANALYSIS The shield shall be designed to withstand all loads and forces occurring from the overburden and hydrostatic pressures and all loads and forces arising from operating the TBM, both in normal mode and in modes required to correct misalignment. The design of the structure of the shield body and other important members shall be supported by FE method calculations under all loading conditions in graphical and numerical form. A Cat 3 check on all critical elements (to be agreed with the Project Manager) shall be carried out and the results forwarded to the Project Manager for acceptance. CUTTERS The cutter head shall incorporate: Cutting tools appropriate for the expected geological conditions with replaceable wear protection. Pick cutters shall have substantial tungsten carbide inserts of grade E3 material equivalent to Sinter-HIP or grade B40 and have their exposed bodies wear protected with chromium carbide composite plate or similar material. Electrical cutter wear indicators shall be fitted to gauge, outer and face pick cutters. Disc cutters shall be a minimum of 17” dia of a type that will revolve in the mixed strata and avoid flats being worn on the tyres, double disc cutters shall be considered. Disc cutters shall lead the pick cutters by a minimum of 50mm at the face. a) Cutter design shall take into account the abrasivity of the ground conditions. The cutters shall be hard faced to a design giving best wear resistance. Thames Water Utilities Limited August 2008 Page 6 of 38
Lee Tunnel, Contract No. 6LYG/A1 PT – Particular Tunnelling Specification - PT200 PT208.3 PT208.4 PT208.5 PT209 PT209.1 PT209.2 PT209.3 PT209.4 Cutters shall be back loaded such that access for repair and replacement can be carried out in safe working condition from within the TBM working chamber. b) Fixed gauge cutting shall be with disc cutters supported by pick cutters. The design shall incorporate a minimum of 6 passes of gauge & semi gauge disc cutters. c) Rescue tooling shall be incorporated in the outer section of cutter head arms. The rescue tools shall be held in reserve and only indexed into use upon failure of normal cutters. The rescue tools shall be used to reach a “safe haven” where free air conditions prevail to allow tool changing. All cutting tools shall be designed to be replaced from the rear face of the cutter head. Consideration shall be given to means of improving the work environment and reducing the duration of tool changing by use of mechanical aids and access ladders. The Contractor shall pay particular attention to protection of the moving (rotating) elements of the machine against the potentially abrasive nature of the ground. The TBM shall be equipped with Chromium Carbide abrasion resistant plating or other approved hard facing to all exposed moving surfaces of the TBM, for example cutting head and screw conveyor. Design components for maximum abrasion resistance and durability. Minimize disc cutter wear to the greatest extent possible when not currently in use to perform tunnel excavation by such means as designing hubs and bearings to allow discs to be readily rotated by hand. CUTTER HEAD The TBM shall incorporate a soil conditioning system for injection directly onto the face. The screw conveyor (if EPBM closed mode) shall also incorporate a facility for soil conditioning. Soil conditioning agents shall be bio-degradable and acceptable for the excavated materials to be used as a fill. All ports shall be independent. The TBM shall be capable of excavating through the ground conditions indicated in the Works Information and Site Information and geological and geotechnical information available to the Contractor without interruption of the excavation operations. The cutter head structure and bearings shall be rated to absorb the maximum forces during tunnelling operations. The cutter head shall incorporate the following:- a) Rotary fluid coupling for transfer of hydraulic fluids. b) Provision to retract the cutter head from the face of the strata without rearward movement of the tail shield. c) An indexing facility to allow probe and ground treatment drilling through the cutter head. d) Bi-directional cutting. e) The cutter head aperture size shall be designed for all anticipated ground conditions as referred to is clause (b) of this section. The proposed aperture size shall be included in the tender information provided by the Contractor. It shall afford adequate ground support and spoil flow features. A cutter head of the open type with a minimum aperture size of 40% shall be provided. f) A method of pre-setting the cutter head to index into the desired tool change positions without the need to open the air lock entry door. Thames Water Utilities Limited August 2008 Page 7 of 38
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080731 6LYG A1 Particular Tunnelling Specification ... - SCATnow

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