1、Section 27 CONCRETE CULVERTS 27.1 GENERAL This work shall consist of fabricating, furnishing, and installing buried precast concrete culverts conforming to these Specifications, the special provisions and the details shown on the plans. Precast reinforced concrete pipe shall be circular, arch or ell
2、iptical, as specified. Precast rein- forced concrete box sections shall be of the dimensions specified or shown on the plans. 27.2 WORKING DRAWINGS When complete details are not provided in the plans, or when required or permitted by provisions in the contract, the Contractor shall prepare and submi
3、t to the Engineer working drawings of the structure or installation system proposed for use. Fabrication or installation of the struc- ture shall not begin until the Engineer has approved the drawings. The working drawings shall show complete de- tails and substantiating calculations of the structur
4、e, the materials, equipment and installation methods the Con- tractor proposes to use. Working drawings shall be submitted sufficiently in advance of the start of the affected work to allow time for review by the Engineer and correction of the submittal by the Contractor without delaying the work. A
5、pproval by the Engineer shall not relieve the Contractor of any re- sponsibility under the contract for the successful comple- tion of this work. 27.3 MATERIALS 27.3.1 Reinforced Concrete Culverts The materials for reinforced concrete culverts shall meet the requirements of the following specificati
6、ons for the classes and sizes specified above. Precast Reinforced Concrete Circular Pipe AASHTO M 170 or AASHTO M 242 (ASTM C 76 or C 655) Arch Pipe AASHTO M 206 (ASTM C 506) Elliptical Pipe AASHTO M 207 (ASTM C 507) Box Sections AASHTO M 259 and AASHTO M 273 (ASTM C 789 and C 850) 27.3.2 Joint Seal
7、ants 27.3.2.1 Cement Mortar Mortar shall be composed of one part Portland cement and two parts sand by volume. Sand shall be well graded and of such size that all will pass a No. 8 sieve. The ma- terials shall be mixed to a consistency suitable for the pur- pose intended and used within 30 minutes a
8、fter the mix- ing water has been added. Admixtures, if any, shall be approved by the Engineer prior to use. 27.3.2.2 Flexible Watertight Gaskets Flexible watertight gasketed joints shall conform to the requirements of AASHTO M 198 and shall be flexible and capable of withstanding expansion, contract
9、ion, and set- tlement of the pipeline. All rubber gaskets shall be stored in as cool a place as practicable, preferably at 70F or less. Rubber gaskets, of the type requiring lubrication, shall be lubricated with the lubricant recommended and sup- plied by the manufacturer of the pipe. 669 670 HIGHWA
10、Y BRIDGES 27.3.2.3 27.3.2.3 Other Joint Sealant Materials Other joint sealant materials shall be submitted for test- ing in advance of their use and shall not be used prior to receiving approval by the Engineer. 27.3.3 Bedding, Haunch, Lower Side and Backfill or Overfill Material 27.3.3.1 Precast Re
11、inforced Concrete Circular, Arch, and Elliptical Pipe Bedding, haunch, lower side and overfill material shall conform to Figures 27.5A, 27.5B, 2732, and 27.5D which define soil areas and critical dimensions, and Ta- bles 27.5A and 27.5B, which list generic soil types and minimum compaction requireme
12、nts, and minimum bed- ding thicknesses for the four Standard Installation Types. The AASHTO Soil Classifications and the USCS Soil Classifications equivalent to the generic soil types in the Standard Installations are presented in Table 27.32. 27.3.3.2 Precast Reinforced Concrete Box Sections For pr
13、ecast reinforced concrete box sections, bedding and backfill material shall conform to Figure 27.5E with the following exceptions. Bedding material may be sand or select sandy soil all of which passes a U.S. Standard Ys-inch sieve and not more than 10% of which passes a U.S. Standard No. 200 sieve.
14、Backfill may be select ma- terial and shall be free of organic material, stones larger than 3 inches in the greatest dimension, frozen lumps, or moisture in excess of that permitting the specified com- paction. 27.4 ASSEMRLY cracks 0.01 inch or less in width are considered acceptable without repair.
15、 Cracks determined to be detrimental shall be sealed by a method approved by the Engineer. 27.4.2 Joints Joints for reinforced concrete pipe and precast rein- forced concrete box sections shall comply with the details shown on the plans, the approved working drawings, and the requirements of the spe
16、cial provisions. Each joint shall be sealed to prevent infiltration of soil fines or water as re- quired by the contract documents. Joint sealant materials shall comply with the provisions of Article 27.3.2. The Contractor shall furnish to the Engineer a certifi- cate of compliance that the material
17、 being furnished con- forms to the joint property requirements. Field tests may be required by the Engineer whenever there is a question regarding compliance with contract requirements. 27.5 INSTALLATION 27.5.1 General Trenches shall be excavated to the dimensions and grade specified in the plans or
18、 ordered by the Engineer. The Contractor shall make such provisions as required to insure adequate drainage of the trench to protect the bed- ding during construction operations. Proper preparation of foundation, placement of foundation material where re- quired, and placement of bedding material sh
19、all precede the installation of the culvert. This shall include necessary leveling of the native trench bottom or the top of founda- tion materials as well as placement and grading of re- quired bedding material to a uniform grade so that the en- tire length of pipe will be supported on a uniform sl
20、ightly yield bedding. The backfill material shall be placed around the culvert in a manner to meet the requirements specified. 27.4.1 General 27.5.2 Bedding Precast concrete units or elements shall be assembled in accordance with the manufacturer?s instructions. All units or elements shall be handle
21、d with reasonable care and shall not be rolled or dragged over gravel or rock. Care shall be taken to prevent the units from striking rock or other hard objects during placement. Cracks in an installed precast concrete culvert that ex- ceed 0.01-inch width will be appraised by the Engineer con- side
22、ring the structural integrity, environmental conditions, and the design service life of the culvert. Generally in non- corrosive environments, cracks O. 10 inch or less in width are considered acceptable; in corrosive environments, those 27.5.2.1 General If rock strata or boulders are encountered un
23、der the culvert within the limits of the required bedding, the rock or boulders shall be removed and replaced with bedding material. Special care may be necessary with rock or other unyielding foundations to cushion pipe from shock when blasting can be anticipated in the area. Where, in the opin- io
24、n of the Engineer, the natural foundation soil is such as to require stabilization, such material shall be replaced by a layer of bedding material. Where an unsuitable material 27.5.2.1 DIVISION II-CONSTRUCTION 67 1 h c 5 v a v b Cu al O al al cn I - o c r U C 1 O I m 7 b Cu Q, O c al Q, Ln I o, C U
25、 U o, o .- a 27.5.2.1 672 HIGHWAY BRIDGES 27.5.2.1 DIVISION II-CONSTRUCTION 673 Ovbrfill - SW. ML. or naunch - Spring Lin See Table 27.58 Lower Side - See Toble 27.58 Bedding - See Table 27.5BJ A,! 1 LiAiddle Bedding loosely placed uncampacted bedding Outer Bedding moterials and comwction each LEGEN
26、D: Bc - Outside Diameter H = Backfill cover above 1 top o pipe side. same requirements as haunch HORIZONTAL ELLIPTICAL PIPE Overfill - SW. LMiddle Bedding loosely placed uncompacled bedding LEGEND Bc Outside Diameter n P Backfill cover obave top of pipe J Outer Bedding materials and compaction each
27、rGf?er% OS haunch VERTICAL ELLIPTEAL PIPE Overfill - SW. ML. or CL Haunch - Spring See Table 27.58 Lower Side - See Table 27.58 Bedding - See Table 27.58J A,! -1 LMiddle Bedding loosely placed Outer Bedding uncompacted bedding mderials and Bc cornpaction each side. same requirements as haunch - Foun
28、dation LEGEND Bc = Outside Diameter H = Bockfiil cover above / lop of pipe ARCH PIPE FIGURE 27.5C Trench Beddings, Miscellaneous Shapes (peat, muck, etc.) is encountered at or below invert eleva- tion during excavation, the necessary subsurface explo- ration and analysis shall be made and corrective
29、 treatment shall be as directed by the Engineer. 27.5.2.3 Precast Reinforced Concrete Box Sections A bedding shall be provided for the type of installation specified conforming to Figure 27.5E unless in the opin- ion of the Engineer, the natural soil provides a suitable 27.5.2.2 Precast Reinforced C
30、oncrete Circular Arch and Elliptical Pipe bedding. A bedding shall be provided for the type of installation specified conforming to Figures 27.5A, 27.5B, 27.5C, and 27.5D which define soil areas and critical dimensions, and Tables 27.5A and 27.5B, which list generic soil types and minimum compaction
31、 requirements, and minimum bed- ding thicknesses for the four Standard Installation Types. 27.5.3 Placing Culvert Sections Unless otherwise authorized by the Engineer, the lay- ing of culvert sections on the prepared foundation shall be started at the outlet and with the spigot or tongue end pointin
32、g downstream and shall proceed toward the inlet 674 HIGHWAY BRIDGES 27.5.3 Overfill Hounch - See Toble 27.5A Lower Side - Sea Toble 273 Spring Li addle Bedding loosely ploced uncompocted bedding / Outer Bedding _-. . . - Foundotion -/ LEGEND: requirements os haunch Bc = Outside Diometer H I Bockfiil
33、 Ewer above top of pipe HORIZONTAL ELUPTICAL PIPE Hounch - See Tobie 27.5A Lower Side - See Toble 27.5A Spring Line Middle Beading Bedding - See Toble 27SAJy,I I loosely ploced Bc uncompocted bedding LEGEND: Bc = Outside Diometer H = Bockfiil cover above top of pipe VERTICAL ELLIPTICAL PIPE Bc/6(Min
34、.) , , Haunch - ke Toble 27% Lower Side - See ToMe 27.9 7 Spring Line -Middle Bedding loosely ploced uncompocted bedding Outer Bedding materials ond Bc/3 compoction each , Foundation UMND side. some requirements Bc = Outside Diometer os haunch H Bockfill Cover Obove top of pipe ARCH PIPE FIGURE 27.5
35、D Embankment Beddings, Miscellaneous Shapes end with the abutting sections properly matched, true to the established lines and grades. Where pipe with bells is installed, bell holes shall be excavated in the bedding to such dimensions that the entire length of the barrel of the pipe will be supporte
36、d by the bedding when properly in- stalled. Proper facilities shall be provided for hoisting and lowering the sections of culvert into the trench without disturbing the prepared foundation and the sides of the trench. The ends of the section shall be carefully cleaned before the section is jointed.
37、The section shall be fitted and matched so that when laid in the bed it shall form a smooth, uniform conduit. When elliptical pipe with circu- lar reinforcing or circular pipe with elliptical reinforcing is used, the pipe shall be laid in the trench in such position that the markings “Top” or “Botto
38、m,” shall not be more than 5” from the vertical plane through the longitudinal axis of the pipe. Multiple installations of reinforced concrete culverts shall be laid with the center lines of individual barrels par- allel at the spacing shown on the plans. Pipe and box sections used in parallel insta
39、llations require positive lateral bearing between the sides of adjacent pipe or box sections. Compacted earth fill, granular backfill, or grout- ing between the units are considered means of providing positive bearing. 27.5.4 Haunch, Lower Side and Backfill or Overfill 27.5.4.1 Precast Reinforced Co
40、ncrete Circular Arch and Elliptical Pipe 27.5.4.1.1 Haunch Material Haunch material shall be installed to the limits shown on Figure 27.5A, 27.5B, 27.5C, and 27.5D. 27.5.4.1.1 DIVISION II-CONSTRUCTION 675 TABLE 27.5A Standard Embankment Installation Soils and Minimum Compaction Requirements Installa
41、tion Type 5Pe 2 (See Note 3.) Type 3 (See Note 3.) Type 4 Bedding Thickness B,/24” minimum, not less than 3”. If rock foundation, use B,/12“ minimum, not less than 6” BJ24” minimum, not less than 3“. If rock foundation, use BJ12” minimum, not less than 6” BJ24“ minimum, not less than 3”. If rock fou
42、ndation, use B,/12” minimum, not less than 6” No bedding required, except if rock foundation, use BJ12” minimum, not less than 6” Haunch and Outer Bedding 95% sw 90% SW or 95% ML 15% SW, 90% ML, or 95% CI, No compaction equired, except if CL, use 85% CL Lower Side 90% SW, 95% ML or 100% CL 85% SW, 9
43、0% ML or 95% CL 85% SW, 90% ML or 95% CL No compaction required, except if CL, use 85% CL NOTES: 1. Compaction and soil symbols-i.e. “95% SW refers to SW soil material with a minimum standard proc- 2. Soil in the outer bedding, haunch, and lower side zones, except within BJ3 from the pipe springline
44、, shall 3. Only Type 2 and 3 installations are available for horizontal elliptical, vertical elliptical and arch pipe. 4. SUBTRENCHES tor compaction of 95%. See Table 27.5C for equivalent modified proctor values. be compacted to at least the same compaction as the majority of soil in the overfill zo
45、ne. 4.1 A subtrench is defined as a trench with its top below finished grade by more than 0.1H or, for roadways, its top is at an elevation lower than 1 below the bottom of the pavement base material. 4.2 The minimum width of a subtrench shall be 1.33 B, or wider if required for adequate space to at
46、tain the specified compaction in the haunch and bedding zones. 4.3 For subtrenches with walls of natural soil, any portion of the lower side zone in the subtrench wall should be at least as firm as an equivalent soil placed to the compaction requirements specified for the lower side zone and as firm
47、 as the majority of soil in the overfill zone, or shall be removed and replaced with soil com- pacted to the specified level. 676 HIGHWAY BRIDGES 27.5.4.1.1 TABLE 27.5B Standard Trench Installation Soils and Minimum Compaction Requirements Installation Type SPe 1 Haunch and Outer Bedding Thickness B
48、edding Bc/24” minimum, not less than 3”. If rock foundation, use BJ12” minimum, not less than 6” 95% sw 5Pe 2 (see Note 3) BJ24“ minimum, not less than 3”. If rock foundation, use BJ12” minimum, not less than 6“ 90% sw or 95% ML 5Pe 3 (see Note 3) Bc/24” minimum, not less than 3“. If rock foundation
49、, use Bc/12” minimum, not less than 6” 85% SW, 90% ML, or 95% CL TYP 4 No bedding required, except if rock foundation, use Bc/12“ minimum, not less than 6” No compaction required, except if CL, use 85% CL Lower Side 90% SW, 95% ML 100% CL, or natural soils of equal firmness 85% SW, 90% ML 95% CL, or natural soils of equal firmness 85% SW, 90% ML 95% CL, or natural soils of equal firmness 85% SW, 90% ML 95% CL, or natural soils of equal firmness NOTES: 1. Compaction and soil symbols-i.e. “95% SW? refers to SW soil material with a minimum standard proctor 2. The trench to
