Drilled Shafts Art. 516.02 SECTION 514. RESERVED SECTION 515. NAME PLATES
515.01 Description. This work shall consist of the furnishing and installing of
name plates.
515.02 Materials. Name plates shall be made of brass, bronze, or other
material as provided by the plans. CONSTRUCTION REQUIREMENTS
515.03 General. The general features of design; the type, size, and spacing
of letters and figures; the items of information to be shown on all name plates for structures constructed under a given contract; and the arrangement of these items shall be as shown on the plans. The surface of the name plate shall be polished.
515.04 Installation. Installation of name plates shall be as follows.
a.Concrete Structures. On concrete structures, the name plate shall be embedded in the concrete and fastened by means of four brass or bronze bolts with countersunk heads, or four lugs cast integral with the plate. The bolts or lugs shall project at least 3 in. (75 mm) into the concrete beyond the back of the plate.
b.Steel Truss. On steel truss spans, the plate shall be fastened on the steel member at the fabricating shop by brazing around the entire perimeter of the plate.
c.Steel Rails. On steel rails, the plate shall be bolted on with four, 3/8 x 1 in. (M10 x 25 mm) stainless steel or brass cap screws that are self-tapping or drilled and tapped in the field.
515.05 Basis of Payment. This work will be paid for at the contract unit price
per each for NAME PLATES. SECTION 516. DRILLED SHAFTS
516.01 Description. This work shall consist of constructing drilled shaft
foundations.
516.02 Materials. Materials shall be according to the following.
Item Article/Section
a.Portland Cement Concrete (Note 1) ....................................................... 1020
b.Reinforcement Bars ........................................................................... 1006.10
c.Grout (Note 1) (Note 2) ...................................................................... 1024.01
d.Permanent Steel Casing ................................................................ 1006.05(d) Art. 516.02 Drilled Shafts Note 1. When soil and ground water sulfate contaminates exceed 500 parts per million, a Type V cement will be required. Note 2. The sand-cement grout mix shall be according to Section 1020 and shall be a 1:1 blend of sand and cement comprised of a Type I or II cement at 185 lb/cu yd (110 kg/cu m). The maximum water cement ratio shall be sufficient to provide a flowable mixture with a typical slump of 10 in. (250 mm).
516.03 Equipment. Equipment shall be according to the following.
Item Article/Section
a.Concrete Equipment ........................................................................... 1020.03
b.Drilling Equipment (Note 1)
c.Hand Vibrator ................................................................................. 1103.17(a) Note 1. The drilling equipment shall have adequate capacity, including power, torque and down thrust, to create a shaft excavation of the maximum diameter specified to a depth of 20 percent beyond the depths shown on the plans.
516.04 Submittals. The following shall be submitted.
a.Qualifications. At the time of the preconstruction conference, the Contractor shall provide the following documentation.
1.References. A list containing at least three projects completed within the three years prior to this project’s bid date which the Contractor performing this work has installed drilled shafts of similar diameter, length, and site conditions to those shown in the plans. The list of projects shall contain names and phone numbers of owner's representatives who can verify the Contractor’s participation on those projects.
2.Experience. Name and experience record of the drilled shaft supervisor, responsible for all facets of the shaft installation, and the drill operator(s) who will be assigned to this project. The supervisor and operator(s) shall each have a minimum of three years experience in the construction of drilled shafts.
b.Installation Procedure. A detailed installation procedure shall be submitted to the Engineer for acceptance at least 45 days prior to drilled shaft construction and shall address each of the following items unless otherwise directed by the Engineer in writing.
1.Equipment List. List of proposed equipment to be used including cranes, drill rigs, augers, belling tools, casing, core barrels, bailing buckets, final cleaning equipment, slurry equipment, tremies, or concrete pumps, etc. Standby equipment shall be available to ensure there is no delay in placing concrete once pouring operations have started. Drilled Shafts Art. 516.05
2.General Sequence. Details of the overall construction operation sequence, equipment access, and the sequence of individual shaft construction within each substructure bent or footing group. The submittal shall address the Contractor’s proposed time delay and/or the minimum concrete strength necessary before initiating a shaft excavation adjacent to a recently installed drilled shaft.
3.Shaft Excavation. A site specific step by step description of how the Contractor anticipates the shaft excavation to be advanced based on their evaluation of the subsurface data and conditions expected to be encountered. This sequence shall note the method of casing advancement, anticipated casing lengths, tip elevations and diameters, the excavation tools used and drilled diameters created. The Contractor shall indicate whether wet or dry drilling conditions are expected or if the water table will be sealed from the excavation.
4.Slurry Quality Control. When the use of slurry is proposed, details covering the measurement and control of the hardness of the mixing water, agitation, circulation, de-sanding, sampling, testing, and chemical properties of the slurry shall be submitted.
5.Shaft Cleaning and Inspection. Method(s) and sequence proposed for the shaft cleaning operation as well as recommendations on how the shaft excavation will be inspected under the installation conditions anticipated.
6.Reinforcement Placement. Details of reinforcement placement including cage centralization devices to be used and method to maintain proper elevation and plan location of cage within the shaft excavation during concrete placement. The method(s) of adjusting the cage length if rock is encountered at an elevation other than as shown on the plans.
7.Concrete Placement. Details of concrete placement including proposed operational procedures for free fall, tremie or pumping methods. The sequence and method of casing removal shall also be stated along with the top of pour elevation, and method of forming through water above streambed.
8.Mix Design. The proposed concrete mix design(s). The Engineer will evaluate the drilled shaft installation procedure and notify the Contractor of acceptance, need for additional information, or concerns with the installation’s effect on the existing or proposed structure(s). CONSTRUCTION REQUIREMENTS
516.05 General. Excavation for drilled shaft(s) shall not proceed until written
authorization is received from the Engineer. The Contractor shall furnish an installation log for each shaft installed. The Contractor shall be responsible for verification of the dimensions and alignment of each shaft excavation as directed by the Engineer. Art. 516.06 Drilled Shafts Unless otherwise approved in the Contractor’s installation procedure, no shaft excavation shall be made within four shaft diameters center to center of a shaft with concrete that has a compressive strength less than 1500 psi (10,300 kPa). The site- specific soil strengths and installation methods selected will determine the actual required minimum spacing, if any, to address vibration and blow out concerns.
516.06 Construction Methods. The construction of drilled shafts may involve
the use of one or more of the following methods to support the excavation during the various phases of shaft drilling, cleaning, and concrete placement dependent on the site conditions encountered. Surface water shall not be permitted to enter the hole. The following are general descriptions indicating the conditions when these methods may be used.
a.Dry Method. The dry method consists of drilling the shaft excavation, removing accumulated water and loose material from the excavation, and placing the reinforcing cage and concrete in a predominately dry excavation. This method shall be used only at sites where the groundwater and soil conditions are suitable to permit the drilling and dewatering of the excavation without causing excessive water infiltration, boiling, squeezing, or caving of the shaft side walls. This method allows the concrete placement by tremie or concrete pumps, or if the excavation can be dewatered, the concrete can be placed by free fall within the limits specified for concrete placement according to Article 516.12.
b.Wet Method. The wet construction method may be used at sites where dewatering the excavation would cause collapse of the shaft sidewalls or when the volume and head of water flowing into the shaft is likely to contaminate the concrete during placement resulting in a shaft defect. This method uses water or slurry to maintain stability of the shaft perimeter while advancing the excavation. After the excavation is completed, the water level in the shaft is allowed to seek equilibrium, the base is cleaned, the reinforcing cage is set, and the concrete is discharged at the base using a tremie pipe or concrete pump, displacing the drilling fluid upwards.
c.Temporary Casing Method. Temporary casing shall be used when either the wet or dry methods provide inadequate support to prevent sidewall caving or ensure excessive deformation of the hole. Temporary casing may also be used to reduce the flow of water into the excavation to allow dewatering, adequate cleaning, and inspection, or to ensure proper concrete placement. Temporary casing left in place may constitute a shaft defect; no temporary casing will be allowed to remain permanently in place without the specific approval of the Engineer. Before the temporary casing is broken loose, the level of concrete in the casing shall be a minimum of 5 ft (1.5 m) above the bottom of the casing. The casing shall not be broken loose by any method which may cause separation of the concrete. After being broken loose and as the casing is withdrawn, additional concrete shall be added to maintain sufficient head so that water and soil trapped behind the casing can be displaced upward and Drilled Shafts Art. 516.08 discharged at the ground surface without contaminating the concrete in the shaft or at the finished construction joint.
d.Permanent Casing Method. When called for on the plans or proposed as part of the Contractor’s accepted installation procedure, the Contractor shall install a permanent casing of the diameter, length, thickness, and strength specified. When permanent casings are used, the lateral loading design requires intimate contact between the casing and the surrounding soils. If the installation procedure used to set the permanent casing results in annular voids between the permanent casing and the drilled excavation, the voids shall be filled with a grout to maintain the lateral load capacity of the surrounding soil, as assumed in the design. No permanent casing will be allowed to remain in place beyond the limits shown on the plans without the specific approval of the Engineer. A grout mix shall be used to fill any visible gaps, which may exist between the permanent casing and either the drilled excavation or temporary casing.
e.Removable Forms. When the shaft extends above the streambed through a body of water and permanent casing is not shown, the portion above the streambed shall be formed with removable casings, column forms, or other forming systems as approved by the Engineer. The forming system shall not scar or spall the finished concrete or leave in place any forms or casing within the removable form limits as shown on the plans unless approved as part of the installation procedure. The forming system shall not be removed until the concrete has attained a minimum compressive strength of 2500 psi (17,200 kPa) and cured for a minimum of 72 hours. For shafts extending through water, the concrete shall be protected from water action after placement for a minimum of seven days.
516.07 Slurry. If the Contractor proposes to use a method of slurry
construction, it shall be submitted with the installation plan. Measures for preventing anomalies from sand fallout shall be included in the plan. During construction, the level of the slurry shall be maintained at a height sufficient to prevent caving of the hole. In the event of a sudden or significant loss of slurry to the hole, the construction of that foundation shall be stopped and the shaft excavation backfilled or supported by temporary casing, until a method to stop slurry loss, or an alternate construction procedure has been approved by the Engineer.
516.08 Excavation Cleaning and Inspection. Materials removed or
generated from the shaft excavations shall be disposed of according to
Article 202 — 03.
After excavation, each shaft shall be cleaned. The cleaning operation shall result in at least 50 percent of the base of each shaft having less than 1/2 in. (13 mm) of sediment or debris at the time of concrete placement. The depth of sediment or debris at any place on the base of the shaft shall be a maximum of 1 1/2 in. (38 mm). Shaft cleanliness shall be determined using the methods as accepted in the installation procedure. A shaft excavation shall be overreamed when, in the opinion of the Engineer, the sidewall has softened, swelled, or has a buildup of slurry cake. Overreaming may Art. 516.09 Drilled Shafts also be required to correct a shaft excavation which has been drilled out of tolerance. Overreaming may be accomplished with a grooving tool, overreaming bucket, or other approved equipment. Overreaming thickness shall be a minimum of 1/2 in. (13 mm).
516.09 Top of Rock. The top of rock will be considered as the point where
rock, defined as bedded deposits and conglomerate deposits exhibiting the physical characteristics and difficulty of rock removal as determined by the Engineer, is encountered which cannot be drilled with earth augers and/or underreaming tools configured to be effective in the soils indicated in the contract documents, and requires the use of special rock augers, core barrels, air tools, blasting, or other methods of hand excavation.
516.10 Design Modifications. If the top of rock elevation differs from that
shown on the plans by more than 10 percent of the length of the shaft above the rock, the Engineer shall be contacted to determine if any drilled shaft design changes may be required. In addition, if the type of soil or rock encountered is not similar to that shown in the subsurface exploration data, the Contractor may be required to extend the drilled shaft length(s) beyond those specified in the plans. In either case, the Engineer will determine if revisions are necessary and the extent of the modifications required.
516.11 Reinforcement. This work shall be according to Section 508 and the
following. The shaft excavation shall be cleaned and inspected prior to placing the reinforcement cage. The reinforcement cage shall be completely assembled prior to drilling and be ready for adjustment in length as required by the conditions encountered. The cage shall be lifted using multiple point sling straps or other approved methods to avoid cage distortion or stress. Additional cross frame stiffeners may also be required for lifting or to keep the cage in proper position during lifting and concrete placement. The Contractor shall attach suitable cage centralizers to keep the cage away from the sides of the shaft excavation during placement and to ensure that at no point will the finished shaft have less than the minimum concrete cover(s) shown on the plans. The cage centralizers or other approved non-corrosive spacing devices shall be used at sufficient intervals (near the bottom and at intervals not exceeding 10 ft (3 m) throughout the length of the shaft) to ensure proper cage alignment and clearance for the entire shaft. If the conditions differ such that the length of the shaft is increased, additional longitudinal bars shall be either mechanically spliced or lap spliced to the lower end of the cage and confined with either hoop ties or spirals. The Contractor shall have additional reinforcement available or fabricate the cages with additional length as necessary to make the required adjustments in a timely manner as dictated by the encountered conditions. The additional reinforcement may be non-epoxy coated.
516.12 Concrete Placement. Concrete work shall be performed according to
Section 503 and the following. Drilled Shafts Art. 516.12 Concrete shall be placed as soon as possible after reinforcing steel is set and secured in proper position. The pour shall be made in a continuous manner from the bottom to the top elevation of the shaft as shown on the contract plan or as approved in the Contractor’s installation procedure. Concrete placement shall continue after the shaft excavation is full and until good quality, uncontaminated concrete is evident at the top of shaft. The elapsed time from the beginning of concrete placement in the shaft to the completion of the placement shall not exceed two hours. At no time during construction shall the slump loss result in a slump below the minimum specified. The Contractor may request a longer placement time provided the concrete mix maintains the minimum specified slump requirements over the longer placement time as demonstrated by trial mix and slump loss tests. Vibration of the concrete will not be allowed when the concrete is displacing drilling fluid or water. In dry excavations, the concrete in the top 10 ft (3 m) of the shaft shall be vibrated. When the top of the shaft is at the finished elevation and no further concrete placement above the finished elevation is specified, the top of the shaft shall be level and finished according to Article 503.15(a). Concrete shall be placed by free fall, tremie, or concrete pump subject to the following conditions.
a.Free Fall Placement. The free fall placement shall only be permitted in shafts that can be dewatered to ensure less than 3 in. (75 mm) of standing water exist at the time of placement without causing side wall instability. The height of free fall placement shall be a maximum of 60 ft (18.3 m) as measured from the discharge end, but it shall be reduced to a maximum of 30 ft (9.1 m) when self-consolidating concrete is used. The Contractor shall obtain approval from the Engineer to place self-consolidating concrete by free fall. Concrete placed by free fall shall fall directly to the base without contacting either the rebar cage or shaft sidewall. Drop chutes may be used to direct concrete to the base during free fall placement. Drop chutes used to direct placement of free fall concrete shall consist of a smooth tube of either one continuous section or multiple pieces that can be added and removed. Concrete may be placed through either a hopper at the top of the tube or side openings as the drop chute is retrieved during concrete placement. The drop chute shall be supported so that free fall does not exceed the specified maximum 60 ft (18.3 m) or 30 ft (9.1 m) at all times from the discharge end, and to ensure the concrete does not strike the rebar cage. If placement cannot be satisfactorily accomplished by free fall in the opinion of the Engineer, either a tremie or pump shall be used to accomplish the pour.
b.Tremies and Concrete Pumps. Tremies shall consist of a tube of sufficient length, weight, and diameter to discharge the initial concrete at the base of the shaft. The tremie shall be according to Article 503.08 and contain no aluminum parts that may have contact with the concrete. The inside and outside surfaces of the tremie shall be clean and smooth to permit both flow of concrete and unimpeded withdrawal during concrete placement. Art. 516.12 Drilled Shafts Pumps and lines may be used for concrete placement and shall have a minimum 4 in. (100 mm) diameter. Tremies and pump lines shall be pre-lubricated with a cement/water mixture, and the excess material wasted before concrete placement begins. The tremie or pump lines used for wet method concrete placement shall be watertight and not begin discharge until placed within 10 in. (250 mm) of the shaft base. Valves, bottom plates, or plugs may be used only when they can be removed from the excavation or be of a material approved by the Engineer that will not cause a defect in the shaft if not removed. The discharge end shall be immersed at least 5 ft (1.5 m) in concrete at all times after starting the pour. Sufficient concrete head shall be maintained in the tremie at all times to prevent water or slurry intrusion in the shaft concrete.
516.13 Construction Tolerances. The following construction tolerances shall
apply to all drilled shafts.
a.Center of Shaft. The center of the drilled shaft shall be within 3 in. (75 mm) of the plan station and offset at the top of the shaft.
b.Center of Reinforcement Cage. The center of the reinforcement cage shall be within 1 1/2 in. (40 mm) of plan station and offset at the top of the shaft.
c.Vertical Plumbness of Shaft. The out of vertical plumbness of the shaft shall not exceed 1.5 percent.
d.Vertical Plumbness of Reinforcement Cage. The out of vertical plumbness of the shaft reinforcement cage shall not exceed 0.83 percent.
e.Top of Shaft. The top of the shaft shall be no more than 1 in. (25 mm) above and no more than 3 in. (75 mm) below the plan elevation.
f.Top of Reinforcement Cage. The top of the reinforcing steel cage shall be no more than 1 in. (25 mm) above and no more than 3 in. (75 mm) below the plan elevation.
g.Excavation Equipment. Excavation equipment and methods used to complete the shaft excavation shall have a nearly planar bottom. The cutting edges of excavation equipment used to create the bottom of shafts in rock shall be normal to the vertical axis of the shaft within a tolerance of 6.25 percent.
516.14 Obstructions. Obstructions shall be defined as any object that cannot
be removed with normal earth drilling procedures, but requires special augers, tooling, core barrels, or rock augers to remove the obstruction. When obstructions are encountered, the Contractor shall notify the Engineer and upon concurrence of the Engineer, the Contractor shall begin working to core, break up, push aside, or remove the obstruction.
516.15 Method of Measurement. This work will be measured for payment in
place and the volume computed in cubic yards (cubic meters). The volume will be Bridge Expansion Joints Art. 520.03 computed using the plan diameter of the shaft multiplied by the measured length of the shaft. The length of shaft in soil will be computed as the difference in elevation between the top of the drilled shaft shown on the plans, or as installed as part of the Contractor’s installation procedure, and the bottom of the shaft or the top of rock (when present) whichever is higher. The length of shaft in rock will be computed as the difference in elevation between the measured top of rock and the bottom of the shaft. When permanent casing is specified, it will be measured for payment in place, in feet (meters). Permanent casing installed at the Contractor’s option will not be measured for payment. Reinforcement furnished and installed will be measured for payment according to
Article 508 — 07.
516.16 Basis of Payment. This work will be paid for at the contract unit price
per cubic yard (cubic meter) for DRILLED SHAFT IN SOIL, and/or DRILLED SHAFT IN ROCK. Permanent casing will be paid for at the contract unit price per foot (meter) for PERMANENT CASING. Reinforcement furnished and installed will be paid for according to Article 508.11. Obstruction mitigation will be paid for according to Article 109.04. SECTION 520. BRIDGE EXPANSION JOINTS
520.01 Description. This work shall consist of constructing bridge expansion
joints.
520.02 Materials. Materials shall be according to the following.
Item Article/Section
a.Preformed Elastomeric Joint Seals for Bridge Decks ........................ 1053.02
b.Preformed Elastomeric Strip Seals for Bridge Decks ......................... 1053.03
c.Structural Steel .................................................................................. 1006.04
d.Neoprene Expansion Joint ...................................................................... 1052
e.Stud Shear Connectors ..................................................................... 1006.32
f.Fabric Reinforced Elastomeric ................................................................ 1028
g.Stainless Steel Hardware .............................................................. 1006.29(d)
h.Chemical Adhesive Resin System ..................................................... 1027.01 CONSTRUCTION REQUIREMENTS
520.03 Steel Fabrication. The plates, angles, and other structural shapes
supporting joint seals shall be fabricated to satisfy shop drawing details and conform to the configuration of the concrete deck or sidewalk. The fabrication shall be according to Articles 505.04 through 505.10. The anchor studs shall be welded prior to painting or galvanizing.
Referenced in this section
DRILLED SHAFTS in other states
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Source: Illinois Standard Specifications for Road and Bridge Construction, 2022 Edition. Pages 430–438 of 1,217. View official source ↗