1、Designation: C891 11Standard Practice forInstallation of Underground Precast Concrete UtilityStructures1This standard is issued under the fixed designation C891; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revi
2、sion. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This practice covers the procedures to be followed in theplanning, site preparation, and installation of undergroundprecast con
3、crete utility structures. Concrete pipe and boxculverts are not covered under this practice. Also, precastconcrete manholes covered in Specification C478 are excludedfrom this practice.1.2 The values stated in inch-pound units are to be regardedas standard. The values given in parentheses are mathem
4、aticalconversions to SI units that are provided for information onlyand are not considered standard.1.3 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and heal
5、th practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2C478 Specification for Precast Reinforced Concrete Man-hole Sections3. Survey3.1 The installation area shall be surveyed using the work-print and a checklist to identify th
6、e work to be done and todetermine that the plans are correct.3.1.1 The location of the utility structure should be where itwill cause minimum interference with traffic and shall beclearly defined on work prints.3.1.2 All underground facilities and structures such as gas,water, sewer, power, telephon
7、e cable, and so forth shall belocated and identified. Location markings shall be placed bythe affected utilities before the construction.3.2 The survey shall identify any obstacles such as overheadwires, building structures, and so forth that will interfere withcrane operations, work progress, or cr
8、eate a safety hazard.Precautionary arrangements shall be made before excavationbegins.3.3 The survey shall give consideration to the soil structureso that proper shoring, sloping, or both, may be planned inadvance of the excavation work.4. Planning4.1 Permits required to do work in accordance with t
9、hedetail plans shall be secured before starting the job. All permitsor a record of the permits shall be retained on the job forimmediate reference.4.2 All utilities and owners of surface and subsurfacefacilities and structures in the area shall be given advancenotification of proposed excavation. Ev
10、ery effort shall be madeto avoid damage to the facilities of others. If any damageoccurs, the owner of the damaged facility shall be notifiedimmediately.4.3 Planning shall include the coordination of all respon-sible parties to ensure that arrangements for removal of brokenpavement, rocks, excess sp
11、oil, and so forth have been made.Responsible parties shall arrange for the delivery, distribution,and storage of required material. If such material cannot bestored on the site, other storage areas must be provided.4.4 Should it appear that a structure location will interferewith traffic, review the
12、 situation with the engineer and notifyappropriate authorities.4.5 Provide for access to call boxes, fire hydrants, etc.5. Safety Requirements5.1 Safety requirements for construction shall be in accor-dance with all federal, state, and local regulations.1This practice is under the jurisdiction of AS
13、TM Committee C27 on PrecastConcrete Products and is the direct responsibility of Subcommittee C27.10 onUtility Structures.Current edition approved Jan. 1, 2011. Published January 2011. Originallyapproved in 1978. Last previous edition approved in 2009 as C891 09. DOI:10.1520/C0891-11.2For referenced
14、 ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Cons
15、hohocken, PA 19428-2959, United States.5.2 The utility structure or any sections that comprise thestructure assembly shall only be lifted at the lifting points sodesignated by the manufacturer.5.2.1 The weight of each section to be handled shall beclearly indicated by marking of the section or clear
16、ly indicatedon the delivery documents.6. Excavating6.1 Coordinate the various excavation operations from thepoint of opening the pavement to completion of backfill so thatthe work area thus occupied is kept to a minimum consistentwith the conditions governing the work. This is particularlyimportant
17、where an excavation is adjacent to hospitals, policeand fire department buildings, service stations, and so forth.6.2 If unforeseen facilities or obstructions are encountered,stop excavating operations immediately. Expose the obstruc-tions with wood handled digging tools and investigate themwith cau
18、tion. If there is any doubt as to the type of obstructionexposed, request positive identification from those suspected ofowning the facility and then proceed as circumstances dictate.6.3 Buried work frequently requires the use of heavyconstruction equipment and transport of heavy loads. Certainsoil
19、conditions may be encountered that will not support theseloads. To avoid hazards and unnecessary delays caused bycave-ins or equipment becoming mired, carefully observe theprevailing conditions beforehand and take appropriate preven-tive measures.6.4 When excavating across highways, streets, alleys,
20、drives, and walks, perform the work in a manner that willminimize interference with traffic. If necessary, bridge theopening with a structure of adequate strength to support anytraffic likely to pass over it. Handrails are required forstructures bridging sidewalk openings.6.5 Inspect excavations aft
21、er every rainstorm or otherhazard-increasing occurrence, and increase the protectionagainst slides and cave-ins, if necessary.6.6 In dewatering excavations, make certain that the dis-charge is carried to a suitable runoff point.6.7 The excavation size must allow for the overall as-sembled height of
22、the utility structure plus the height of collarsections, a manhole frame and cover, and any bedding materialrequired. The excavation shall have sufficient width and length,in accordance with local, state, and federal regulations, toensure safe installation and compaction of the backfill.7. Shoring7.
23、1 Shoring for construction shall be in accordance with allfederal, state, and local regulations.7.2 Install shoring by starting at the top of the excavationand working down. Take care to place braces and jacks in a truehorizontal position with proper vertical spacing. Braces mustbe firmly secured to
24、 prevent kickouts.7.3 All materials used for shoring must be in good conditionand of the right size. Do not use timbers with large loose knots.Prefabricated box type shoring is permitted provided it is cleanand structurally sound after previous use.7.4 Installation of the shoring should follow close
25、ly theexcavation work even if no work is being done in theexcavation. The longer an excavation is left unsupported, thegreater the chance of a cave-in.7.5 As soon as the work in the excavation is completed andthe utility structure has been installed, remove the shoring andcomplete the backfilling, u
26、nless otherwise instructed by au-thorities. Remove the shoring from the bottom up. Release thejacks or braces slowly. Use chains or wire ropes to pull out thejacks or braces from above.8. Installation Procedures8.1 Consult the detailed plan for the proper orientation ofthe precast concrete utility s
27、tructure to ensure proper alignmentwith entering cables, pipes, or conduits.8.2 Do not place damaged precast concrete sections unlessapproved by the customer.8.3 Do not field modify the structure unless it is determinedthat such modifications (for example, cuts to form slots orholes) will not advers
28、ely affect the strength of the structure.8.4 Do not install structures under conditions known toresult in loads heavier than that for which the structure wasdesigned.8.5 After the excavation has been completed to the requireddimensions specified on the detailed plan, level off the areawhere the base
29、 section will be located. If necessary, to providea more level and solid foundation, fill in and compact the finesoil, sand, or gravel. Set the base as level as possible so anywater in the structure will drain toward the sumps.8.6 Assemble the multisection utility structures by loweringeach section
30、into the excavation. Lower, set level, and firmlyposition the base section before placing the additional sections.8.7 Where the possibility exists of a watertight structurebecoming buoyant in a flooded excavation, take necessarysteps to avoid flotation of the structure.8.8 To ensure joint integrity
31、when joining sections ofprecast concrete structures, give particular attention to remov-ing all foreign materials such as dirt, mud, and stones fromjoint surfaces and see that all sealing materials are placedproperly.8.9 The sealing material provided for the joints betweensections may be installed i
32、n accordance with the sealantmanufacturers recommendations at the job site or at themanufacturers plant.8.10 If a mortar grout is to be used as a seal, clean andmoisten all surfaces to be grouted. The grout should be of aconsistency so that it will not flow when applied. Apply themortar grout in a m
33、anner to ensure filling of all voids in thejoint being sealed.8.11 Apply the mortar grout in an amount to provide aminimum of38-in. (10-mm) thickness of mortar on all jointsurfaces. After assembly, dress the interior joints to removeexcess mortar.8.12 If a misalignment of sections occurs during inst
34、alla-tion, remove the appropriate section. If the sealing material isdamaged, clean the joint surfaces before repairing or placingnew sealing material. Avoid misalignment of sections by usingguide devices attached to the lower section to position theupper section into place.C891 1129. Backfilling an
35、d Restoration9.1 Do the backfilling as soon as possible after the utilitystructure has been placed.9.2 Excavations shall meet or exceed requirements of thelocal permit granting authority and backfilled with a granularmaterial free from large stones, rocks, pavement, and so forth.Expansive soil mater
36、ial shall not be used as backfill around thestructure.9.3 When a precast concrete utility structure is placed in anunpaved area, slope the area around the entrance frame andcover to provide drainage away from the entrance cover. Slopethe final grading upward to within 1 in. (25 mm) of the topsurface
37、 of the frame and cover.9.4 Backfill ProceduresBackfilling shall be achieved byusing lifts (layers) or flooding (jetting) the excavation to therequired compaction. Lifts shall be placed uniformly around allsides of the installed section and compacted in accordance withproject requirements.9.5 Restor
38、ation of the area where the utility structure wasinstalled shall meet the requirements of the local grantingauthority or the property owner.9.6 Followup inspections for settlement are required.Should settlement occur, the contractor shall be responsible forthe necessary repair to restore the area to
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42、ed a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of
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