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

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Lee Tunnel, Contract No. 6LYG/A1 PT – Particular Tunnelling Specification - PT300 PT309.8 PT309.9 PT310 PT310.1 PT310.2 PT310.3 PT311 PT311.1 PT311.2 PT312 PT312.1 PT312.2 PT312.3 PT313 PT313.1 For SPBM, the TBM shall be designed to work under all conditions described in the Contract Documents. 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. For SPBM, the design of the slurry treatment plant shall accommodate the types and quantities of geological materials anticipated and to remove solids from the suspension at a sufficiently fast rate so that the slurry treatment does not limit the TBM advance rate. The slurry shall be reconditioned or replaced with fresh slurry when the slurry properties are unsatisfactory. SEALS Provide main bearing seals rated for tunnelling conditions and maximum pressure anticipated from the sum of all forces acting on the seals simultaneously and all machine operating characteristics related to the main bearings. Design the seals for the articulation joint, tail shield and probe ports for maximum hydrostatic and earth pressure. Shield tail seals shall incorporate a redundant system of wire brushes to seal against maximum hydrostatic and cavity grout pressure with due consideration of the liner segment design and the influence of liner grouting in seal design. Provide a minimum of three seals continuously fed with fibrous grease whenever the TBM advances. Tail seals other than the rear seal shall be replaceable from within the tunnel during a drive. GROUTING Cavity Grouting: Provide a computer operated grouting system linked to TBM systems to calculate grout quantities and continuously adjust grout injection rate and pressure on the basis of the TBM advance rate and other data. The annulus void between the tunnel lining extrados and the excavated ground shall be fully grouted with a grouting system and mix approved by the Project Manager SEGMENT ERECTOR The segment erector shall be compatible with the TBM and liner system to ensure safe and efficient segment installation and shall have an appropriate factor of safety for the anticipated loads. The erector shall be capable of actuation in the axial, radial, and circumferential directions and in the three articulation angles corresponding to the six degrees of freedom. Design the erector to grip and erect the segments so that they are positioned accurately, so that segments are aligned within the required tolerances, so that gaskets are fully compressed, and so that no damage or distortion of the segments occurs. All hand held electrical equipment, such as the pendant controls for the segment erector, shall be in a watertight enclosures and the control circuit protected by a Ground Fault Interrupter Circuit. TBM/SEGMENTAL LINING INTERFACE Concrete segments and associated items shall be designed for anticipated ground and water loads and environmental conditions on the completed tunnel. The Contractor shall ensure that the segments are compatible with its selected construction equipment, means, methods and procedures including, but not limited to alignment control, handling, erecting, jacking and grouting. Thames Water Utilities Limited August 2008 Page 6 of 15
Lee Tunnel, Contract No. 6LYG/A1 PT – Particular Tunnelling Specification - PT300 PT313.2 PT313.3 PT313.4 PT313.5 PT314 PT314.1 PT314.2 PT314.3 PT314.4 PT315 PT315.1 PT315.2 PT315.3 Maximum ram thrust contact pressure at any point and any time on the liner system ram thrust shall not exceed 50% of the segment 28-day compressive strength. Thrust pads are to be designed such that they shall not damage gaskets or segments. Equip TBM to allow continuous, complete backfill grouting of the annulus between the concrete segments and excavated surface. Tail seal grease shall be compatible with the liner system gaskets and materials, shall be inert, shall not contaminate the surrounding ground or groundwater and shall not in any way cause the long term deterioration of the liner concrete, the joint connector, the gaskets, seals or joint packers. CONTROL AND INTERLOCKS The TBM cutter head shall be prevented from moving at any point during any maintenance or entry. An interlock should be provided from the control cabin to allow remote inching operation of the cutter head. Contractor to establish safety procedures, for approval by the Engineer, which will include, among other issues, a procedure to ensure that all personnel have evacuated the cutter head and front chamber before any movement is undertaken. This provision is intended to assist cutter tool changes with local indexing of the cutter head. The cutter head drive shall have fail-safe braking system to prevent inadvertent movement. All erector load-holding functions shall have a fail safe alarm system. Rotational drives shall be fitted with fail safe brakes. The segment erector shall be fitted with the selection and audibility of safe lifting alarms. An interlock shall be provided that prevents extension of the shove rams should grout delivery through the tail skin be interrupted or blocked. The Contractor shall provide a method of automatic data logging and measuring volume and pressure of grout injected per tunnel lining ring. GUIDANCE SYSTEM The Contractor shall provide a TBM Guidance and Control System with laser theodolite. This shall be a commercially manufactured system. Technical Aspects a) Reference should be made to Contract Documents for required accuracy and tolerance and other matters affecting the operation of the system. b) The tunnelling system shall be designed to maintain a clear space for the guidance system and laser beam, irrespective of shield or TBM orientation. c) The data shall be presented on displays at the underground Machine Procedural Aspects The operation of the guidance system shall be a specific feature of the Contractor’s Quality Assurance Plan. This should clearly address: a) Definition of responsibility and authority of personnel maintaining and operating the guidance system. b) Intervals between manual checking of data produced by the guidance system (lengthened intervals may be adopted as experience is gained) c) Intervals at which survey control points are to be established, based upon tunnel geometry and guidance system characteristics. Thames Water Utilities Limited August 2008 Page 7 of 15
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080731 6LYG A1 Particular Tunnelling Specification ... - SCATnow

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