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6-16 Soldier Pile and Soldier Pile Tieback Walls6-16 Soldier Pile and Soldier Pile Tieback Walls
6-16.1 Description
This Work consists of constructing soldier pile walls and soldier pile tieback walls.
6-16.2 Materials
Materials shall meet the requirements of the following sections: Controlled Density Fill (CDF) 2-09.3(1)E Lean Concrete 6-02.3(2)D Cement 9-01 Aggregates for Concrete 9-03.1 Gravel Backfill 9-03.12 Premolded Joint Filler 9-04.1(2) Welded Shear Studs 9-06.15 Steel Reinforcing Bar 9-07.2 Epoxy-Coated Steel Reinforcing Bar 9-07.3 Paints 9-08 Timber Lagging 9-09.2 Preservative Treatment for Timber Lagging 9-09.3(1) Soldier Piles 9-10.5 Concrete Curing Materials and Admixtures 9-23 Fly Ash 9-23.9 Water 9-25 Prefabricated Drainage Mat 9-33.2(3) Other materials required shall be as specified in the Special Provisions.
6-16.3 Construction Requirements
6-16.3(1) Quality Assurance
The steel soldier piles shall be placed so that the centerline of the pile at the top is within 1 inch of the Plan location. The steel soldier pile shall be plumb, to within 0.5 percent of the length based on the total length of the pile. Welding, repair welding, and welding inspection shall conform to the Section 6-03.3(25) requirements for welding, repair welding, and welding inspection for all other steel fabrication.
6-16.3(2) Submittals
The Contractor shall submit Type 2 Working Drawings consisting of shop plans as specified in Section 6-03.3(7) for all structural steel, including the steel soldier piles, and shall submit Type 2 Working Drawings consisting of shop plans and other details as specified in Section 6-17.3(3) for permanent ground anchors. The Contractor shall submit Type 1 Working Drawings consisting of the permanent ground anchor grout mix design and the procedures for placing the grout to the Engineer for approval. The Contractor shall submit Type 2E Working Drawings consisting of forming plans for the concrete fascia panels, as specified in Sections 6-02.3(16) and 6-02.3(17) .
1.Where the lateral pressure from concrete placement, as specified in Section
6-02 3(17)J, is less than or equal to the design earth pressure, the Contractor may tie
forms directly to the soldier piles. M 41-10 Page 6-257 Soldier Pile and Soldier Pile Tieback Walls 6-162. Where the lateral pressure from concrete placement, as specified in Section
6-02 3(17)J, is greater than the design earth pressure, the Contractor shall follow one
of the following procedures:
a.Tie the forms to strongbacks behind the lagging, or use some other system that confines the pressure from concrete placement between the lagging and the form panels, in addition to the ties to the soldier piles.
b.Reduce the rate of placing concrete to reduce the pressure from concrete placement to less than or equal to the design earth pressure in addition to the ties to the soldier piles.
c.Follow a procedure with a combination of a. and b.
3.The Contractor shall design the forms for an appropriate rate of placing concrete so that no cold joints occur, considering the wall thickness and height, and volume of concrete to be placed. The Contractor shall submit Type 2 Working Drawings consisting of a shaft installation plan. In preparing the submittal, the Contractor shall reference the available subsurface data provided in the Contract test hole boring logs and the geotechnical report(s) prepared for this project. This plan shall provide at least the following information:
1.An overall construction operation sequence and the sequence of shaft construction.
2.List, description, and capacities of proposed equipment including but not limited to cranes, drills, augers, bailing buckets, final cleaning equipment, and drilling units. The narrative shall describe why the equipment was selected, and describe equipment suitability to the anticipated site and subsurface conditions. The narrative shall include a project history of the drilling equipment demonstrating the successful use of the equipment on shafts of equal or greater size in similar soil/rock conditions.
3.Details of shaft excavation methods including proposed drilling methods, methods for cleanout of the shafts, disposal plan for excavated material and drilling slurry (if applicable), and a review of method suitability to the anticipated site and subsurface conditions.
4.Details of the method(s) to be used to ensure shaft stability during excavation and concrete placement (e.g., using temporary casing, slurry, or other means to prevent caving or bottom heave). This shall include a review of method suitability to the anticipated site and subsurface conditions. If temporary casings are proposed, casing dimensions and detailed procedures for casing installation and removal shall be provided. If slurry is proposed, detailed procedures for mixing, using, maintaining, and disposing of the slurry shall be provided. A detailed mix design, and a discussion of its suitability to the anticipated subsurface conditions shall also be provided for the proposed slurry.
5.Details of soldier pile placement including internal support bracing and centralization methods.
6.Details of concrete placement including proposed operational procedures for pumping and/or tremie methods.
7.Details of the device used to prevent unauthorized entry into a shaft excavation.
8.The method to be used to form the horizontal construction joint at the top elevation specified for concrete Class 4000P in the shaft. Page 6-258 M 41-10
6-16 Soldier Pile and Soldier Pile Tieback Walls6-16.3(3) Shaft Excavation
Shafts shall be excavated to the required depth as shown in the Plans. The minimum diameter of the shaft shall be as shown in the Plans. The excavation shall be completed in a continuous operation using equipment capable of excavating through the type of material expected to be encountered. The Contractor may use temporary telescoping casing to construct the shafts. If the shaft excavation is stopped the shaft shall be secured by installation of a safety cover. It shall be the Contractor’s responsibility to ensure the safety of the shaft and surrounding soil and the stability of the sidewalls. A temporary casing, slurry, or other methods specified in the shaft installation plan shall be used if necessary to ensure such safety and stability. Where caving in conditions are encountered, no further excavation will be allowed until the Contractor has implemented the method to prevent ground caving as submitted in accordance with item 4 of the Shaft Installation Plan. No more than 2 inches of loose or disturbed material, for soldier piles with permanent ground anchors, nor more than 12 inches of loose or disturbed material, for soldier piles without permanent ground anchors, shall be present at the bottom of the shaft just prior to beginning concrete placement. The excavated shaft shall be inspected and receive acceptance by the Engineer prior to proceeding with construction. When obstructions are encountered, the Contractor shall notify the Engineer promptly. An obstruction is defined as a specific object (including, but not limited to, boulders, logs, and previously fabricated objects) encountered during the shaft excavation operation that prevents or hinders the advance of the shaft excavation. When efforts to advance past the obstruction to the design shaft tip elevation result in the rate of advance of the shaft drilling equipment being significantly reduced relative to the rate of advance for the rest of the shaft excavation, then the Contractor shall remove the obstruction under the provisions of Section 6-16.5 . The method of removal of such obstructions, and the continuation of excavation shall be as proposed by the Contractor and approved by the Engineer. Excavation of shafts shall not commence until a minimum of 12 hours after the shaft backfill for the adjacent shafts has been placed. The temporary casings for the shafts shall be removed. A minimum 5-foot head of concrete shall be maintained to balance the soil and water pressure at the bottom of the casing. The casing shall be smooth.
6-16.3(4) Installing Soldier Piles
Soldier piles, if spliced, shall conform to all requirements of Section 6-05.3(6) . The prefabricated steel soldier piles shall be lowered into the drilled shafts and secured in position. Concrete cover over the soldier pile shall be 3 inches minimum, except that the cover over the soldier pile flange plate reinforcing at permanent ground anchor locations shall be 1½ inches minimum. The steel soldier piles and attachments shall be shop painted after fabrication to the limits shown in the Plans with one coat of inorganic zinc primer. Application of the one coat of primer shall be in accordance with Section 6-07 . The welded shear studs may be attached before or after painting. Paint damaged by welding shear studs in place does not require repair. M 41-10 Page 6-259 Soldier Pile and Soldier Pile Tieback Walls 6-166-16.3(5) Backfilling Shaft The excavated shaft shall be backfilled as shown in the Plans and subject to the following requirements:
1.Dry shaft excavations shall be backfilled with CDF or lean concrete.
2.Wet shaft excavations shall be backfilled with lean concrete, placed in accordance with the requirements for seal concrete in Section 6-02.3(6)B, except the minimum tube diameter shall be 4 inches.
3.Lean concrete shall meet the requirements of Section 6-02.3(2)D .
4.A wet shaft is defined as a shaft where water is entering the excavation and remains present to a depth of 6 inches or more.
5.When the Plans or test hole boring logs identify the presence of a water table at or above the elevation of the bottom of soldier pile shaft, the excavation shall be considered as wet, except as otherwise noted. Such a shaft may be considered a dry shaft provided the Contractor furnishes and installs casing that is sufficiently sealed into competent soils such that water cannot enter the excavation. Placement of the shaft backfill shall commence immediately after completing the shaft excavation and receiving the Engineer’s approval of the excavation. Vibration of shaft backfill is not required. If water is not present, the shaft backfill shall be deposited by a method that prevents segregation of aggregates. The shaft backfill shall be placed such that the free-fall is vertical down the shaft without hitting the sides of the soldier pile or the excavated shaft. The Contractor’s method for depositing the shaft backfill shall have approval of the Engineer prior to the placement of the shaft backfill.
6-16.3(6) Designing and Installing Lagging and Installing Permanent Ground Anchors
Lagging for soldier pile walls shall conform to one of the following two categories:
1.Temporary lagging is defined as lagging that is in service as a structural member for a maximum of 36 months before a permanent load-carrying fascia is in place, except for the following exception: Lagging for soldier pile walls in site soils conforming to an excluded soil type as defined under Section 6-16.3(6)A will be classified as permanent lagging conforming to Section 6-16.3(6)C , in which case this requirement will be specified in the Plans along with design details for such lagging.
2.Permanent lagging is defined as all lagging not conforming to the definition of temporary lagging as specified in category 1, above.
6-16.3(6)A Soil Classification
For the purposes of designing lagging for soldier pile walls, soils shall be categorized in the classifications defined below. Soil Type 1 The following shall be considered Type 1 soils:
1.Cohesive fine-grained soils either CL or CH of medium consistency with γH/Su < 5.
2.Cohesive fine-grained soils either CL or CH that are stiff to very stiff and nonfissured.
3.Fine-grained soils either ML or SM-ML that are above the water table.
4.Coarse-grained soils either GW, GP, GM, GC, SW, SP, or SM that are medium dense to dense. Page 6-260 M 41-10
6-16 Soldier Pile and Soldier Pile Tieback WallsSoil Type 2
The following shall be considered Type 2 soils:
1.Cohesive fine-grained soils either CL or CH that are heavily overconsolidated and fissured.
2.Fine-grained ML soils or coarse-grained SM-ML soils that are below the water table.
3.Coarse-grained SC soil that is medium dense to dense and is below the water table.
4.Coarse-grained soils either SW, SP, or SM that are loose. Soil Type 3 The following shall be considered Type 3 soils:
1.Cohesive fine-grained soils CL and CH that are soft with γH/Su > 5.
2.Fine-grained slightly plastic ML soil that is below the water table.
3.Coarse-grained SC soil that is loose and below the water table. Exclusions Regardless of whether site soils conform to one of the soil types defined above, site soils under the following conditions are excluded from the Type 1, Type 2, and Type 3 soil classifications:
1.Disturbed soils such as those in landslides or known unstable areas.
2.Layered soils dipping into the excavation steeper than 4H:1V. Lagging for soldier pile walls located in site soils excluded from the Type 1, Type 2, and Type 3 soil classifications shall be designed in accordance with the latest AASHTO LRFD Bridge Design Specifications with current interim specifications. Use of the table in Section
6-16.3(6)B for timber lagging in these situations will not be allowed.
6-16.3(6)B Temporary Lagging
The Contractor shall design temporary lagging for all soldier pile walls. The temporary lagging design shall be based on the following:
1.The AASHTO LRFD Bridge Design Specifications , latest edition with current interim specifications, except that timber members used for temporary lagging may be selected based on the table below.
2.The soil type as specified in the Plans or as determined from the geotechnical report prepared for the project.
3.The soil pressure diagram, either as shown in the Plans or as included in the geotechnical report prepared for the project, including the surcharge for temporary construction load when shown in the Plans. The Contractor shall submit Type 2E Working Drawings consisting of the soldier pile wall lagging design details and supporting design calculations. The submittal shall include, at a minimum, the following:
1.Description of the material used for the lagging, including identification of applicable material specifications.
2.Installation method and sequence.
3.If the lagging material is to be removed during or after installation of the permanent fascia, a description of how the lagging is removed without disturbing or damaging the fascia, soldier piles, and retained soil, and a description of how, and with what material, the void left by the removal of lagging is to be filled. M 41-10 Page 6-261 Soldier Pile and Soldier Pile Tieback Walls 6-164. For all cases, except with timber for temporary lagging, a description with appropriate details of how subsurface drainage is to be accommodated, either in accordance with Section 6-16.3(7) for timber lagging, Section 6-15.3(7) for shotcrete facing, or other means appropriate for the geotechnical site conditions and acceptable to the Engineer for other lagging materials. Lagging materials and lagging installation methods that cause the buildup of, and prevent the relief of, pore water pressure will not be allowed. Free-draining materials are defined as those materials that exhibit a greater permeability than the material being retained. Temporary lagging may be untreated timber conforming to the Section 9-09.2 requirements specified under Structures for timber lagging or another material selected by the Contractor. Timber for temporary lagging shall conform to the minimum actual thickness specified in the table below for the soil type, exposed wall height, and lagging clear span as shown in the Plans. Notwithstanding the requirements of Section 1-06.1 , steel materials used by the Contractor as temporary lagging may be salvaged steel provided that the use of such salvaged steel materials shall be subject to visual inspection and acceptance by the Engineer. For salvaged steel materials where the grade of steel cannot be positively identified, the design stresses for the steel shall conform to the Section 6-02.3(17)B requirements for salvaged steel, regardless of whether rivets are present or not. Minimum Actual Thickness of Timber Used as Temporary Lagging Soil Type1 1 1 2 2 3 3 3 Exposed Wall Height (feet)25 and underOver 25 to 6025 and underOver 25 to 6015 and underOver 15 to 25 Over 25 Clear Span of Lagging (feet)Minimum Actual Thickness of Rough Cut Timber Lagging (inches)3 5 2 3 3 3 3 3 4 6 3 3 3 3 3 4 5 7 3 3 3 4 4 5 6 8 3 4 4 4 5 6 See Note2 9 4 4 4 5 See Note2See Note2See Note2 10 4 5 5 5 See Note2See Note2See Note2 1Soil Type as defined in Section 6-16.3(6)A . 2For exposed wall heights exceeding the limits in the table above, or where minimum rough cut lagging thickness is not provided, the Contractor shall design the lagging in accordance with the latest AASHTO LRFD Bridge Design Specifications with current interim specifications. 3Table modified from FHWA document “Lateral Support Systems and Underpinning” (Report No. FHWA-RD-75-130).
6-16.3(6)C Permanent Lagging
Permanent lagging, including timber, shall be as shown in the Plans. The use of the table in Section 6-16.3(6)B for the design of timber lagging for permanent lagging will not be allowed. Page 6-262 M 41-10
6-16 Soldier Pile and Soldier Pile Tieback Walls6-16.3(6)D Installing Lagging and Permanent Ground Anchors
The excavation and removal of CDF and lean concrete from the shaft for the lagging installation shall proceed in advance of the lagging and shall not begin until the CDF or lean concrete in the shaft is of sufficient strength that the material remains in place during excavation and lagging installation. If the CDF or pumpable lean concrete separates from the soldier pile, or caves or spalls from around the soldier pile, the Contractor shall discontinue excavation and lagging installation operations until the CDF or lean concrete is completely set. The bottom of the excavation in front of the wall shall be level. Excavation shall conform to Section 2-03 . The lagging shall be installed from the top of the soldier pile proceeding downward. For walls without permanent ground anchors, the bottom of excavation at any one time shall not be more than 3 feet below the bottom level of the lagging installed up to that time, but in no case shall the depth of excavation beneath the bottom level of installed lagging be such to cause instability of the excavated face. For walls with permanent ground anchors, the bottom of excavation shall be not more than 3 feet below the permanent ground anchor level until all permanent ground anchors at that level are installed and stressed, but in no case shall the depth of excavation beneath the permanent ground anchor level be such to cause instability of the excavated face. Installing, stressing, and testing the permanent ground anchors shall be in accordance with Section 6-17 and the construction sequence specified in the Plans.
6-16.3(6)E Backfill Behind Lagging
The lagging shall make direct contact with the soil. When and where lagging is not in full contact with the soil being retained, either the lagging shall be wedged back to create contact or the void shall be filled with a free-draining material. Caving that occurs during excavation shall be backfilled with free-draining material. When utilizing lagging in fill situations, the backfill layers shall be placed in accordance with Section 2-03.3(14) except that all layers shall be compacted to 90 percent of maximum density.
6-16.3(7) Prefabricated Drainage Mat
For walls with concrete fascia panels, a 4-foot-wide strip of prefabricated drainage mat shall be installed full height of the concrete fascia panel, centered between soldier pile flanges, unless otherwise shown in the Plans. The prefabricated drainage mat shall be attached to the lagging in accordance with the manufacturer’s recommendations. The fabric side shall face the lagging. Splicing of the prefabricated drainage mat shall be in accordance with the manufacturer’s recommendations. The Contractor shall ensure the hydraulic connection of the prefabricated drainage mat to the previously installed material so that the vertical flow of water is not impeded. The Contractor shall tape all joints in the prefabricated drainage mat to prevent concrete intrusion during concrete fascia panel construction.
6-16.3(8) Concrete Fascia Panel
The Contractor shall construct the concrete fascia panels as shown in the Plans, and in accordance with the forming plan. The concrete fascia panels shall be cured in accordance with the Section 6-02.3(11) requirements specified for retaining walls. The Contractor shall provide the specified surface finish as noted, and to the limits shown, in the Plans to the exterior concrete surface. When noted in the Plans, the Contractor shall apply pigmented sealer to the limits shown in the Plans. Asphalt or cement concrete gutter shall be constructed as shown in the Plans. M 41-10 Page 6-263 Soldier Pile and Soldier Pile Tieback Walls 6-166-16.4 Measurement Soldier pile shaft construction will be measured by the linear foot of shaft excavated below the top of ground line for the shaft, defined as the highest existing ground point within the shaft diameter. Furnishing soldier pile will be measured by the linear foot of pile assembly specified in the Proposal, including adjustments to the Plan quantity made in accordance with Section 1-04.4 . Lagging will be measured by the square foot area of lagging installed. The quantity will be computed based on the vertical dimension from the highest lagging elevation to the lowest lagging elevation between each pair of adjacent soldier piles as the height dimension and the center-to-center spacing of the soldier piles as the length dimension. Prefabricated drainage mat will be measured by the square yard of material furnished and installed. Concrete fascia panel will be measured by the square foot surface area of the completed fascia panel, measured to the neat lines of the panel as shown in the Plans.
6-16.5 Payment
Payment will be made for each of the following Bid items when they are included in the Proposal: “Shaft - ___ Diameter”, per linear foot. All costs in connection with constructing soldier pile shafts shall be included in the unit Contract price per linear foot for “Shaft - ___ Diameter”, including shaft excavation, temporary casing if used, CDF, lean concrete, concrete Class 4000P, and installing the soldier pile assembly. “Furnishing Soldier Pile - ___”, per linear foot. All costs in connection with furnishing soldier pile assemblies shall be included in the unit Contract price per linear foot for “Furnishing Soldier Pile - ___”, including fabricating and painting the pile assemblies, and field splicing and field trimming the soldier piles. Payment will be made based on the quantity specified in the Proposal unless changes are made to this quantity in accordance with Section 1-04.4 , in which case the quantity specified in the Proposal will be adjusted by the amount of the change and will be paid for in accordance with Section 1-04.4 . “Lagging”, per square foot. All costs in connection with furnishing and installing lagging shall be included in the unit contract price per square foot for “Lagging”, including design of temporary lagging and filling voids behind the lagging with a free-draining material as approved by the Engineer. “Prefabricated Drainage Mat”, per square yard. “Concrete Fascia Panel”, per square foot. All costs in connection with constructing the concrete fascia panels as specified shall be included in the unit Contract price per square foot for “Concrete Fascia Panel”, including all steel reinforcing bars, premolded joint filler, polyethylene bond breaker strip, joint sealant, PVC pipe for weep holes, exterior surface finish, and pigmented sealer (when specified). Unless otherwise specified, all costs in connection with non-shaft excavation, including all excavation required for placement of timber lagging, shall be included in the unit Contract price per cubic yard for “Roadway Excavation” or “Roadway Excavation Incl. Haul” as specified in Section 2-03.5 . Page 6-264 M 41-10
6-16 Soldier Pile and Soldier Pile Tieback Walls“Removing Soldier Pile Shaft Obstructions”, estimated.
Payment for removing obstructions, as defined in Section 6-16.3(3) , will be made for the changes in shaft construction methods necessary to remove the obstruction. The Contractor and the Engineer shall evaluate the effort made and reach agreement on the equipment and employees utilized, and the number of hours involved for each. Once these cost items and their duration have been agreed upon, the payment amount will be determined using the rate and markup methods specified in Section 1-09.6 . For the purpose of providing a common proposal for all bidders, the Contracting Agency has entered an amount for the item “Removing Soldier Pile Shaft Obstructions” in the bid proposal to become a part of the total bid by the Contractor. If the shaft construction equipment is idled as a result of the obstruction removal work and cannot be reasonably reassigned within the project, then standby payment for the idled equipment will be added to the payment calculations. If labor is idled as a result of the obstruction removal work and cannot be reasonably reassigned within the project, then all labor costs resulting from Contractor labor agreements and established Contractor policies will be added to the payment calculations. The Contractor shall perform the amount of obstruction work estimated by the Contracting Agency within the original time of the contract. The Engineer will consider a time adjustment and additional compensation for costs related to the extended duration of the shaft construction operations, provided:
1.The dollar amount estimated by the Contracting Agency has been exceeded, and;
2.The Contractor shows that the obstruction removal work represents a delay to the completion of the project based on the current progress schedule provided in accordance with Section 1-08.3 .
Source: Washington Standard Specifications for Road, Bridge, and Municipal Construction, 2024 Edition. Pages 610–618 of 1,151.