Draft. Not Yet Approved SECTION 10.1 GENERAL SCOPE DEFINITIONS

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1 SECTION 10.1 GENERAL SCOPE This part of the Manual covers the structural design and installation of reinforced concrete pipe for railway culverts. Pipe geometry may be circular, arch, or elliptical DEFINITIONS Pipe Installation Conditions a. Trench Installation. The pipe is installed in a relatively narrow trench excavated in undisturbed soil and then covered with backfill extending to the ground surface. b. Positive Projecting Embankment Installation. The pipe is installed on original ground or compacted fill with the top of the pipe above the ground, or compacted fill and then covered with embankment. c. Negative Projecting Embankment Installation. The pipe is installed within a relatively narrow trench with the top of the pipe below the natural ground or compacted fill, and then covered with embankment. d. Induced Trench Installation. The pipe is installed in a trench, backfilled with compressible material over the pipe, and then covered by a high embankment. e. Jacked or Tunneled Installation. The pipe is installed without removal of the ground above the pipe. Grouting of the exterior annular space around the pipe may be required to ensure full contact with the soil around the pipe. If existing soil conditions require an oversized tunnel, or if anticipated service conditions require access to the pipeline, a carrier pipe may be installed within the tunnel or casing pipe Direct Bury Pipe Installation Types Concrete Pipe may be installed in accordance with the requirements for a Type 1 through Type 4 Installation as shown in Figure , and defined in Tables , and The default installation for design shall be a Type 2 Installation, unless otherwise designated by the Engineer.

2 Figure Standard Trench/Embankment Installation (Circular Pipe shown; also applies to arch and elliptical pipe)

3 Table Standard Installations Soil and Minimum Compaction Requirements (Note: Compaction is a percentage of ASTM D698)

4 Table Equivalent USCS and AASHTO Soil Classifications for Soil Designations

5 Symbols B c = Outside width of the pipe (ft) B d = Width of the pipe trench (ft) B f = Bedding factor, defined as the ratio between the supporting strength of buried pipe to the strength of the pipe determined in the three- edge bearing test obtained according to requirements of ASTM Designation C497. B fe = Bedding factor for earth loads; the ratio of maximum moment in the three- edge bearing test to the maximum moment in the buried condition when the vertical soil load and three- edge bearing load are equal. B fll = Bedding factor for live loads; the ratio of maximum moment in the three- edge bearing test to the maximum moment in the buried condition when the vertical live load and the three- edge bearing load are equal. Coeff d = Coefficient of live load distribution through the pipe. D = inside diameter (or horizontal width) of the pipe (in) D o = outside diameter (or horizontal width) of the pipe (in) D- Load = the supporting strength of a pipe loaded under three- edge bearing test conditions, expressed in pounds per linear foot, per foot of inside diameter or horizontal span. (lbs/ft/ft) D 0.01 = the maximum three- edge bearing test load supported by a concrete pipe before a crack having a width of 0.01 inch occurs throughout a continuous length of 1 foot. (lbs/ft/ft) D ult = the maximum three- edge bearing test load supported by a concrete pipe Dist = Distribution of live load through the pipe (ft) FS = Factor of Safety; normally taken as 1.0 for the D 0.01 inch service D- load. H = Height of cover over the top of the pipe (ft) taken from the base of rail to the top of the pipe (ft.) I = the impact load applied to the top of the pipe as a fraction of the live load. L T = Length of tie (ft) IM = impact load factor

6 P = Train Axle Load (lbs) = 80,000 lbs for Cooper E- 80 Loading S = axle spacing (ft.) = 5 ft. between 80 kip axles S i = inside span of pipe (in) w = unit weight of the backfill material (lbs per cubic foot) W E = earth loads transmitted to the pipe (lbs per linear foot) W F = weight of fluid carried in the pipe (lbs per linear foot) W l = live load at the top of the pipe (lbs per square foot) W L = live load including impact transmitted through the pipe (lbs per linear foot) W S = other loads transmitted to the pipe (lbs per linear foot) PIPE SECTION 10.2 MATERIALS Pipe shall conform to the following ASTM Standards for type, size, shape, manufacturing, testing and strength requirements as specified by the Engineer. a. ASTM Designation C76, Specification for Reinforced Concrete Culvert, Storm Drain, and Sewer Pipe. b. ASTM Designation C506, Specification for Reinforced Concrete Arch Culvert, Storm Drain, and Sewer Pipe. c. ASTM Designation C507, Specification for Reinforced Concrete Elliptical Culvert, Storm Drain, and Sewer Pipe. d. ASTM Designation C655, Specification for Reinforced Concrete D- Load Culvert, Storm Drain, and Sewer Pipe RUBBER GASKETS Rubber gaskets, if specified, shall conform to ASTM Designation C443, Specification for Joints for Concrete Pipe and Manholes, Using Rubber Gaskets ACID RESISTANT COATINGS OR LINERS Acid resistant coatings or liners shall be specified by the Engineer for the particular condition required.

7 SECTION 10.3 DESIGN GENERAL The design of reinforced concrete pipe culverts must take into account the type of installation and bedding, the soil constants of the natural ground and backfill, the relative settlements of the pipe, pipe foundation, bedding, backfill and natural ground, acidity of the flow, the physical measurements such as depth of cover and width of cut, determination of earth load, live load, impact, and any additional loading REFERENCES Satisfactory design methods, utilizing more exact design procedures, are referenced for the use of the Engineer. a. American Concrete Pipe Association Concrete Pipe Design Manual b. American Concrete Pipe Association Concrete Pipe Handbook c. ASCE 15-98, Standard Practice for the Direct Design of Buried Precast Reinforced Concrete Pipe Using Standard Installations (SIDD) LOADS a. Design loading on the pipe shall include Dead (Earth) Load, Live (Railroad) Load, Impact, and any other surcharge loads. Unless otherwise specified by the Engineer, Live (Railroad) Load shall be Cooper E 80. Earth Loads and Cooper E 80 Live Loads may be obtained from Figure

8 Figure Loads on Concrete Pipe b. The Engineer may use the equation below to determine the earth load transmitted to the pipe. Other acceptable methods of analyses are given in Article W E = 1.45 x B c x H x w EQ c. Track loading to be supported by the pipe is shown in Figure The indicated loading includes a variable Impact Load of 40% at 1.5 feet below the base of rail, and 0% at 10 feet. The equation for this is shown below: IIII = EQ d. The Engineer may calculate the E 80 live load on the pipe in (psf) by dividing the 80 kip axle load by the 5 foot spacing length between axles, and a total width of 8 feet for the track

9 plus the load distribution through the height of cover using a ratio of 1:1 as shown in Figure : Figure Live Load Distribution Through the Soil e. The following equation may be used to calculate the live load at the top of the pipe in pounds per square foot: WW = EQ f. Where the live load spread from multiple tracks running side by side overlap (center- to- center spacing of tracks is less than L T + H), the live load distribution shall consider the area that encompasses the spread from all interacting tracks. That load shall be assumed uniform over the entire area of the live load spread.

10 g. When the live load reaches the top of the pipe, it is further dissipated through the structure of the pipe a distance of: Coeff d = 242 D o Dist = Coeff d x D o < 54 inches EQ EQ h. Live load pressure at the top of the pipe is independent of the direction the train travels with respect to the axis of the pipe. i. For track running perpendicular to the longitudinal axis of the pipe, the live load in pounds per linear foot for design shall be: WW = EQ For track running parallel to the longitudinal axis of the pipe, the live load in pounds per linear foot for design shall be: WW = WW BB EQ j. Any surface surcharges, other than track load shall be converted to additional height of fill to determine their loading on the pipe. k. Loading on a carrier pipe, that is within a casing pipe, shall be taken as the full Dead + Live + Impact Load without consideration of the presence of the casing, unless the casing is permanently protected from corrosion using such means as providing extra pipe thickness or a resistant coating. l. If a trench design is utilized, the design trench width shall be indicated on the construction drawings as a maximum width of trench. The minimum width of trench shall be B c +2 feet, or 1.33 B c, whichever is greater.

11 BEDDING FACTORS a. Earth load bedding factors to be used in the equation for determination of the D- Load shall be obtained from Table or as permitted by interpolation. Pipe Installation Methods Standard Installation Types (Note 1) Tunnel Direct Bury (Note 2) D = 12 inches D = 24 inches D = 36 inches D = 72 inches D = 144 inches Jacked or Tunneled (all 3.0 sizes) Carrier Pipe (all sizes) Casing Pipe (all sizes) 3.0 Note 1: See Figure and Tables and Note 2: For pipe diameters other than listed in Table , earth load bedding factors can be obtained by interpolation Table Earth Load Bedding Factors

12 b. Live load bedding factors to be used in the equation for determination of the D- Load shall be obtained from Table , or as permitted by interpolation. Fill Height (ft) Pipe Diameter, inches Note 1: For pipe diameters other than listed in Table , B fll values can be obtained by interpolation Note 2: For fill heights equal to or greater than 6.5 feet, the live load bedding factor shall be MINIMUM PIPE STRENGTH Table Live Load Bedding Factors Pipe subjected to track loads shall have a minimum strength of D 0.01 = 1350 lbs/ft/ft (Class III) even if analysis indicates that a lower D- Load is satisfactory FACTOR OF SAFETY The standard Factor of Safety of 1.0 against a 0.01 inch crack D- Load should be used for design unless the Engineer indicates that a higher factor of safety is required PIPE STRENGTH The required D- Load of the pipe shall be determined by the following equation: D. = + EQ. 10-8

13 ALTERNATE DESIGN PROCEDURE In lieu of carrying out the complete design analysis required by these guidelines, the Engineer may choose the required pipe strength for E 80 loading based on Table Class III = Class IV = Class V = 1350 lbs/ft/ft 2000 lbs/ft/ft 3000 lbs/ft/ft Type 2 Installation_ Inside Diameter, Di (inches) Fill Height (ft) From Base of Rail to Top of Pipe Table Reinforced Concrete Pipe Fill Height Tables for E 80 Loading

14 Inside Diameter, inches Type 2 Installation Fill Height (ft) Table Reinforced Concrete Pipe Fill Height Tables for E 80 Loading (Cont.) Notes: Values in the Table are D- Load values for the D 0.01, D- Load strengths of the pipe in lbs/ft/ft. The assumptions used to determine the values in the table are: o W = 120 pcf unit weight of soil o Live Load = E 80 o Installation Type = Type 2 Installation using a granular soil compacted to 90% Standard Proctor o Installation Condition = positive projecting embankment condition

15 PREPARATION OF SUBGRADE Excavation SECTION 10.4 INSTALLATION a. Trenches shall be excavated in accordance with bank stability requirements to a width sufficient to allow for proper joining of the pipe and thorough compaction of the bedding and backfill material under and around the pipe. The completed trench bottom shall be firm and cleaned for its full length and width. b. The pipe trench bottom shall be cambered longitudinally if settlement after installation is expected. If camber of the pipe trench is required, the indicated camber must be shown on the plans. c. Where specified on the plans, the excavation for a pipe to be placed within embankment fill shall be made after the embankment has been completed to the specified height above the top of the pipe Foundation a. If the foundation is incapable of supporting the pipe loads, an adequate support shall be specified or approved by the Engineer PIPE INSTALLATION Laying Pipe a. Pipe laying shall begin at the downstream end of the culvert. The bell or groove end of the pipe shall be placed upstream. No culvert shall be put into service until a suitable outlet is provided for the water. b. Elliptical pipe shall be placed with the vertical axis within 5 degrees of a vertical plane through the longitudinal axis of the culvert Bedding a. Pipe bedding and placement shall be specified to conform to one of the Installations denoted in Table b. When pipe cannot be placed on a prepared surface, but must instead be placed on an unprepared surface, the installation shall be considered to be a Type 4 Installation. Type 4 Installations should only be used for emergency work, and are not recommended for

16 permanent installations unless authorized by the Engineer. For typical Type 4 Installations, see Figure , and Table Joining Pipe a. Pipe may either be bell and spigot or tongue and groove design unless otherwise specified. When bell pipe is used, a shallow excavation shall be made underneath the bell of sufficient depth so that the bell does not rest on the bedding material. b. Pipe sections shall be joined so that the ends are fully entered and the inner surface areas are flush and even per pipe manufacturer s recommendations. c. Joints shall be made with grout, rubber gaskets, plastic mastic compounds, or other combination of these types as approved and specified by the Engineer. Mortar joints in pipe that is jacked into place shall not be sealed with mortar until the culvert jacking is complete. d. In areas where pipe sections could separate, suitable ties should be specified to prevent pipe section separation. e. Endwalls or headwalls may be used for culverts under tracks and designed to resist pipe separations as well as to retain the embankment Leak Resistance If leak resistant joints are required, rubber gasketed pipe is recommended. When such joints are specified, the pipe should be tested for infiltration and exfiltration as specified by the Engineer. The maximum rate of leakage shall conform to the following accepted requirements, or to other standards set forth by the Engineer. Infiltration 0.6 gallons per hour per inch of diameter per 100 feet of pipe Exfiltration 0.6 gallons per hour per inch of diameter per 100 feet of pipe when subjected to an internal head of 2 feet, and increased by 10% for each additional 2 feet of head Culverts Carrying High Acid Fluids Where the ph of the conducted fluid is less than 4.5, the internal surfaces of the culvert shall be protected from acid attack by a suitable permanent coating or liner. The Engineer shall specify the type of protection and the means of application.

17 BACKFILL AND EMBANKMENT General a. The backfill around the culvert shall be placed in accordance with the installation requirements denoted in Table and Figure , and other requirements of Section 8, Part 10. b. All culverts that are to carry track load shall have the backfill thoroughly compacted to a minimum density of 95% as determined by ASTM D698, and as specified elsewhere in the project specifications for adjacent embankment Embankment Bedding a. Where rock or noncompressible foundation material is encountered, the hard unyielding material should be excavated below the elevation of the bottom of the pipe or pipe bell to a depth in accordance with Table , or ½ inch for each foot of fill over the top of the pipe, whichever is greater, but need not be more than ¾ of the diameter (or horizontal span) of the pipe. b. For a negative projecting embankment condition, the width of the excavation, B d, shall be at least 1.33 B c and with a minimum of 2 feet greater than the outside diameter of the pipe for thorough filling and compaction of the void space under the pipe haunch Trench Bedding a. Materials for backfill on each side of the pipe for the full width of the trench and to an elevation of 1 foot above the pipe shall not contain frozen lumps, stones that would be retained on a 2 inch sieve, chunks, highly plastic clay, or other objectionable material. Granular backfill material shall have 100% passing a ¾ inch sieve, not less than 95% passing a ½ inch sieve, and not less than 95% retained on a No. 16 sieve. Oversized material shall be removed at the source of the material, except as directed by the Engineer. b. When the top of the pipe is even with or below the top of the trench, backfill material shall be placed at or near the optimum moisture content and compacted in layers not exceeding 6 inches (compacted) on both sides of the pipe for the full required length. c. Backfill material shall be placed and compacted for the full depth of the trench, unless induced trench installation is used.

18 d. When the top of the pipe is above the top of the trench, backfill shall be placed at or near optimum moisture content and compacted in layers not exceeding 6 inches (compacted) and shall be brought up evenly on both sides of the pipe for its full length to an elevation 1 foot above the top of the pipe. The width of backfill on each side of the pipe for the portion above the top of the trench shall be equal to twice the diameter of the pipe or 12 feet, whichever is less. The backfill material used in the trench section and the portion above the top of the trench for a distance on each side of the pipe equal to the horizontal diameter and to 1 foot above the top of the pipe shall conform to the requirements for backfill in paragraph a. The remainder of the backfill shall meet the requirements for embankment construction. e. The width of the trench B d, shall be 1.33 B c, but not less than 2 feet greater than the outside diameter of the pipe in order to completely fill the void Induced Trench Method (Special Design) a. The Induced Trench method shall not be used when the pipe is subjected to track loading without making a complete investigation of settlements involved. b. When the Induced Trench method is used, design and installation requirements shall follow the recommendations set forth in the references in Article The embankment shall be completed as required in Article to a height above the pipe equal to the vertical outside diameter of the pipe plus 1 foot. A trench equal in width to the outside horizontal diameter of the pipe, in depth equal to the vertical outside diameter of the pipe, and to the length shown on the plans shall then be excavated to within 1 foot of the top of the pipe, trench walls being as nearly vertical as possible. This trench shall be loosely filled with highly compressible material. Construction of the embankment above the pipe shall then proceed in a normal manner using regular fill material. c. The length of the Induced Trench method shall be determined by the Engineer in keeping with the design assumptions and the pipe strength being used. d. When the Alternate Induced Trench method is used, the embankment shall be constructed in a normal manner to a height above the culvert bedding elevation equal to twice the outside diameter of the pipe. A trench as required shall then be excavated with the walls as nearly vertical as possible, and the pipe bedded and backfilled to 1 foot above the pipe as called for in Article The remaining portion of the trench shall then be loosely filled with highly compressible material. Construction of embankment shall then proceed in a normal manner. e. In no case shall the length of compressible material extend to the ends of the culvert.

19 f. Rock fill shall not be dumped over the culvert without a sufficient cushion of earth to prevent breakage of the pipe Jacking Pipe a. Pipe used for jacking shall form a continuous smooth outside surface when placed in contact with the adjacent pipe. The tongue or spigot shall preferably be at the downstream end. Jacking frames shall be so constructed as to avoid breaking the pipe or forcing it out of alignment. The pipe shall preferably be jacked upgrade in order to provide drainage at the heading during excavation. Satisfactory means shall be provided for maintaining the lead pipe at the correct line and grade. b. The pipe shall be installed according to plans and specifications. The contractor s submittal shall document the construction procedure, extra pipe reinforcement, jack shield (if required), jacking pit location, shoring, estimated deformation, track monitoring procedures, and other features for the safe and satisfactory completion of the work. Plans prepared by the contractor giving the construction details shall be submitted to the Engineer for review. c. Voids created during jacking operations shall be filled with a suitable grout material. Grout shall be pumped through grout ports integrally cast into the pipe, or drilled after production. Locations shall be recorded after mining is completed. d. Monitor elevation and alignment of the railroad track above during the jacking procedures. Jacking must be stopped and any problems corrected if track movement is detected Installing Pipe in Tunnels When it is necessary to place culvert pipe by tunneling, plans and specifications for the completed structure shall be prepared by the Engineer. The contractor shall set forth the construction procedures and other necessary details and submit them to the Engineer for review.