SECTION PRECAST CONCRETE SEGMENTAL TUNNEL LINING

Transcription

1 SECTION PRECAST CONCRETE SEGMENTAL TUNNEL LINING PART 1 - GENERAL 1.1 DESCRIPTION A. The Work specified in this Section consists of the requirements for manufacturing, installing, erecting and performing operations necessary or incidental to provide complete precast concrete bolted, gasketed segments for final liner rings in tunnels and special segments at breakouts for cross-passages, including necessary labor, materials, tools and equipment to obtain a gas and water tight tunnel. B. Design concrete segments, gaskets, and associated items for anticipated ground and water loads and environmental conditions on the completed tunnel. Check and provide segments that are compatible with selected construction equipment, means, methods, and procedures including, handling, erecting, jacking, and grouting. C. Design, furnish and install tapered rings to accommodate changes in tunnel alignment. 1.2 QUALITY CONTROL A. Comply with Section , Project Quality Program Requirements Design Build. B. Qualifications of Manufacturer 1. Employ qualified firm regularly engaged in manufacture and fabrication of precast concrete tunnel lining segments of similar dimensions and tolerances to those specified. C. Dimensional Tolerances 1. Develop required tolerances for erection, water-proofing, and gas-proofing. Determine the minimum segment manufacturing and installation tolerances compatible with these performance requirements, 2. Fabricate segments to dimensions and tolerances as shown on approved Shop Drawings. Use closer tolerances if necessary for erection, watertightness or gastightness. 3. Provide labor, equipment, templates, and facilities necessary for inspecting manufactured segments. 4. Segment Manufacturer - Design and implement a tolerance measurement system to account and adjust for thermal, moisture, and ambient temperature influences. C

2 5. Manufacture similar segments with such accuracy and uniformity in dimensions that they will be entirely interchangeable not only in individual rings but also with segments of other rings. D. Tunnel Liner Ring Installation Tolerances as shown on approved Shop Drawings. E. Demonstration Liners Before starting production manufacturing of precast concrete lining segments, prepare two demonstration liners each composed of three complete precast concrete segmental rings to show proposed method of construction within approved tolerances. 1. Furnish a 15-day written advance notice to Metro before start of Demonstration Liner assembly. 2. Assemble entire demonstration liner rings at the Worksite or another approved location above ground. Build the rings stacked vertically with bolts and dowels on a flat level base with staggering radial joints. No packing or gaskets are to be used in Demonstration Liners. Provide temporary support structures, such as bracing as required. 3. Maintain demonstration liners intact until tolerances of completed rings are verified. Keep one of the demonstration liner rings as master rings for the duration of segment casting operations to be used for verifying compliance with fabrication tolerances for the production segments and checking selected segments on the matching and spacing of bolt holes, dowels, and interchangeability of segments. 4. If demonstration liners are not approved, dismantle liners, adjust forms, cast new segments, and erect new demonstration liners for acceptance. Continue until demonstration liners are acceptable. Perform this work at no additional cost to the Metro. F. Production Units - Do not commence production manufacturing before obtaining Metro approval of the demonstration liners. G. Source Quality Control - Factory Tests 1. Provide written notice at least 30 days before starting manufacture of segments to allow Metro to inspect place and means and methods of fabrication. 2. At a minimum frequency of one of every hundred castings from each form, randomly pick segments to form rings on the master rings to ensure that tolerances and interchangeability of segments are being maintained. Reject unacceptable segments and other segments cast from the same form. 3. Allow Metro access to work areas, and provide sufficient office space, assistance, and equipment for performing the inspections and preparing reports. 4. Provide three certified tests each satisfactorily demonstrating, in embedded condition, the following: Minimum (yield) pullout capacity on circumferential joint connector assemblies and (yield) pullout capacity on radial joint bolt assemblies. C

3 Include actual joint connector assemblies. H. Markings - Markings such as logos, trademarks and proprietary information, except panel identification markings, are prohibited on surfaces of tunnel liner segments. I. Acceptance Segments with cracks or honeycombing are not acceptable. Segments not meeting tolerances or minimum strength requirements will be rejected. Damage to gasket grooves in excess of 5 percent of the length along edge side of segment or damage or cracking around bolt holes shall be cause for rejection. J. Chloride Ion Penetrability As determined by ASTM C1202. Test mix designs and field cured specimens representing each 1,000 segments fabricated. K. Select the required gasket material and perform materials property tests on fabricated processed gasket compound specimens to ensure that gaskets meet the performance requirements, including tensile strength, elongation, hardness, compression set, ozone resistance, aging, stress relaxation, shrinkage and permeability. 1.3 REFERENCE STANDARDS: A. American Concrete Institute (ACI) B. American Society for Testing and Materials (ASTM) 1.4 SUBMITTALS A. Refer to Section , Submittal Procedures. B. Shop Drawings: 1. Complete details of formwork, reinforcing, mechanical joint connection assemblies, joint reliefs, gasket grooves, gaskets, inserts, and accessories necessary for manufacture, transportation and erection. 2. Segment dimensions and tolerances. 3. Tunnel Liner Ring Installation Tolerances including: a. Variation of interior diameter b. Segment face lipping or offset C. Concrete mix as specified in Section , Portland Cement Concrete. D. Material specifications for components of joint connection system and specifications describing pullout capacity and material properties of the assemblies. E. Certifications and Qualifications: 1. Experience of Gasket Suppliers - Demonstrate that tunnel liner gaskets have C

4 performed successfully in tunneling operations of similar applications. 2. Precast Concrete Segment Manufacturer Include name and location of segment manufacturer; names and experience of personnel managing the precast concrete plant; and list of comparable tunnel projects and names of client contacts where manufacturer's segments have been used. F. Detailed description of procedures for manufacturing, casting, curing, handling, transporting, storing, erecting and repairing segments. Include plans to control shrinkage and temperature cracking of segments and the gasket manufacturer's quality control plan ensuring consistency of gasket material, dimensions, and installation. G. Details of tolerance measurement system, including equipment details, master and working template configurations and layout, types and numbers of gauges and calipers used to determine accuracies and tolerances in manufacture. H. Samples of all components and accessories. I. Methods to protect gaskets from direct sunlight and weather if stored outside. J. Gasket material property and performance testing results. K. Procedure and products for bolt pockets, lifting sockets, and cast or drilled holes. L. Segment repair and rejection criteria. PART 2 - PRODUCTS 2.1 CONCRETE A. As specified in Section , Portland Cement Concrete, Class 6500 minimum. 2.2 REINFORCING STEEL A. As specified in Section , Concrete Reinforcement. A.B. Do not use steel fibers as primary concrete reinforcement. 2.3 WELDED WIRE FABRIC A. Conform to ASTM A185, cold bent, free of contamination or damage. B. Use concrete spacers. 2.4 INSERTS AND ANCHORS A. Inserts and anchors - ASTM A36 steel, hot-dip galvanized in accordance with ASTM A123. C

5 2.5 GASKETS A. Water and gas proofing double gaskets on all mating faces with connected double gaskets by a cross gaskets to compartmentalize joints between intrados and extrados gaskets. located on each radial joint face. B. Dense elastomeric synthetic rubber type; free of blisters, porosity, pittings, and other imperfections; manufactured as a continuous frame, with fully molded gasket corners mitered on each side; and vulcanized to provide uniform gasket thickness along entire length of mating surfaces. C. Gasket material shall not suffer any adverse effects when exposed to the soil or groundwater at pressures up to specified design pressure. Refer to Geotechnical Baseline Report (GBR) for descriptions on soil and groundwater constituents. D. Design gaskets to withstand 1.5 times the larger of the maximum working water pressure and the maximum segment backfill grouting pressure as specified in Section , Tunnel Grouting, at maximum possible joint gap and offset. E. Maximum methane transmission rate of eight milliliters per square meter per day through a 1.5 inch thick gasket at 10 psi pressure differential. F. Performance 1. Gasket Groove Loads - Demonstrate through a combination of engineering analysis and laboratory experiments that gasket will be gas tight and will not exert a load that may damage the concrete gasket groove of concrete tunnel liner under any combination of manufacturing and installation tolerances. 2. Groove - Designed for selected gaskets. 3. Water tightness a. Provide watertight seals even when complete closure of concrete tunnel liner segments is not possible because of manufacturing and installation tolerances. b. Prove by laboratory testing that at T-shaped joint between two tunnel liner rings (three liner segments) gasket will resist, without leakage, the specified design water pressure under a combination of gasket differential gap and gasket bearing surface offset conditions. c. Gasket differential gap is defined as difference between gasket deflection at optimum gasket compression and actual gasket deflection as tested (in a direction normal to the applied compressive load). 4. Prediction of Future Performance - Demonstrate by combination of engineering analysis and measured performance of gasket that gasket may be expected to perform its intended function over a design life of 100 years. G. Gasket Adhesive - As recommended by gasket supplier to secure gasket to groove. C

6 2.6 COMPRESSION PACKING A. Bituminous fiber-board compression joint packers. B. If used, design joints to allow full closure of gaskets with compression packing in place. Compression packing shall fill less of the area between gaskets and fully compress against abutting segments. 2.7 MECHANICAL JOINT CONNECTOR SYSTEMS A. Nuts - ASTM A536, hot dip galvanized. B. Washers - ASTM F436 hot dip galvanized. C. Bolts - ASTM A307, hot dip galvanized. Select bolt sizes to meet performance requirements. D. Grommets - Configured to seal bolt holes under conditions of maximum misalignment. E. Dowels - Fiber reinforced engineered thermoplastic. Ring formed pliable elastic surface. Select dowel sizes to meet performance requirements. PART 3 - EXECUTION 3.1 DESIGN A. Design segments for: 1. Ground and hydrostatic loads 2. Loads across joint connections to maintain joint and installation performance. 3. Invert loads derived from transport of equipment and materials. 4. Loads generated by handling and erection. 5. Loads generated by tunnel boring machine (TBM) shove. 6. Loads generated by grouting. 7. Seismic loads 8. Radial joints as a convex/convex joint for all loading conditions including seismic loading. B. WORKMANSHIP Furnish segments to be mechanically connected across joint faces. 1. Provide joint connection assemblies to facilitate structural performance, to achieve and maintain maximum joint close down, to achieve required gasket C

7 compression and ring circularity, and to assist in ring stabilization. 2. Furnish bolted joint assembly system for circumferential joints (non enhanced liners only) at Contractor's Option. 3. Provide minimum two bolt assemblies for each radial (longitudinal) joint connection. C. Provide gasket grooves and gaskets as specified herein. 1. Design joint to prevent lip, which forms outside edge of gasket groove from contact with opposing lip during erection and thrusting of adjoining ring 2. Prevent damage and spalling. 3. For joint surfaces upon or against which gasket may bear, provide surfaces that are smooth, free of spalls, fractures and imperfections that would adversely affect performance of joint. 4. Design segment joints to withstand forces caused by compression of gasket, without cracking or fracturing. D. Provide compression packings on joint faces. 1. Design circumferential joint to provide full closure of gaskets with compression packing in place, and to prevent over compression and damage to gaskets from thrust loads and loads across mechanical connections. 2. Design longitudinal joints to provide full closure of gaskets when the segments are in contact. E. Completely remove lifting devices intruding into tunnel space. F. Clean lifting sockets, connector pockets, and cast or drilled holes, then fill with nonshrink epoxy mortar. G. Provide positive means of identifying each segment, indicating the following information: 1. Internal diameter of the liners. 2. Concrete specification. 3. Segment type designation. 4. Manufacturer's name or initials. 5. Date of manufacture. 6. Serial number. 3.2 FORMWORK C

8 A. Fabricate concrete forms with machined steel mating surfaces to provide tolerances required. B. Ensure segments of common design and cast in different molds are interchangeable. C. Provide forms with individual identification to ensure that all segments cast are marked and fully traceable. 3.3 SEGMENT PREPARATION A. Make concrete spacers from the same concrete mix design as the segments, and compacted and cured to the same standards as the segments. B. Do not use plastic spacers. 3.4 SEGMENT CASTING A. Finishing: 1. Formed Surfaces - Smooth form finish 2. Extrados - Provide a finish smooth and free from blemishes to ensure an adequate seal can be achieved within the tail skin of tunnel boring machine. B. Ensure the in-place strength of concrete prior to lifting. 3.5 INSTALLATION OF GASKET A. Place gaskets into grooves provided around segments, in accordance with manufacturer's recommendations. 3.6 ERECTION OF TUNNEL LINING A. Construct rings to correct line and grade, in true circular form to preserve the circular form of tunnel, and preserve true plane of face of rings, and in a manner, which will not throw ring out of position or dislodge previously erected rings. B. Inspect concrete segments, joint connection assemblies, joint packings and gaskets before being taken underground and just before erection. Pay attention to imperfections and damage; repair or replace to the satisfaction of Metro. C. Install segmented tunnel lining system to dimensions and tolerances for line, grade and circularity; within required design tolerances for joint and structural performance.assemble and make joint connections to adjoining ring segment inside shield. Keep shield invert clean and free of soil before erection of each ring. Satisfactorily clean joint surfaces of segments immediately before erection. D. Dowels can be used across circumferential joints. Maintain full gasket closure after erection. E. If bolt down joint connectors are used across circumferential joints, satisfy approved C

9 minimum design load in bolts at time of erection before jacking of shield ahead of segment ring. Maintain full gasket closure after erection. F. Do not add packings or materials to joints to adjust line and grade or negotiate curves. G. Do not use segment bolts or other positively interlocking elements to compress segment gaskets, but only to maintain segment gaskets in the compressed position H. Stagger radial joints in adjacent rings. Erected rings in any sequence provided that keys remain above springline. Rings may be rotated one or more bolt locations to meet line, grade and curve requirements, provided that only T-Joints result at any given point between adjacent rings. I. Hangers for utility lines necessary for construction of tunnel may be connected to concrete segments; do not interfere with proper erection of each ring. Cast or drilled holes or embedded anchorages may be used as reviewed and approved by Designer. J. Completed tunnels - Water and gas tightness as specified in Section , Excavation by Tunnel Boring Machine. 3.7 REPAIR OF DEFECTS A. Develop classification of damage and required repairs. B. Repair or replace structurally damaged and misaligned segments to satisfaction of Designer. C. Clean and repair, before erection, all oil stained and unsightly rings. Clean all rings that have been become stained during or after erection. D. Maintain structural integrity, durability and gas and water tightness of segmented lining system. 3.8 INSPECTION OF PRECAST CONCRETE SEGMENTS A. Metro will have the right to inspect, check and reject finished segments not found to be in accordance with these specifications. B. To measure and determine accuracy of manufacture, provide and make available at all times, master templates and working templates, gauges, calipers and other equipment as may be required to inspect the segments. END OF SECTION C