02 - 31 63 33 00 REV.pdf

TFI-F22 UPGRADE MUNITIONS COMPLEX KNMD069215

JOINT BASE PEARL HARBOR-HICKAM, HAWAII

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SECTION 316333

FOUNDATION PILING (MICROPILES)

PART 1 - GENERAL

1.01 SUMMARY:

A. Work under this Section consists of furnishing all necessary design, supervision, labor, materials, and equipment required for the installation of micropiles as indicated on the drawings.

B. Micropile capacities shall be as follows:

1. The design pile capacities for the Type I micropiles shall be as follows:

a. The minimum net allowable compression capacity shall be 120 kips. The minimum ultimate compression capacity shall be 240 kips, with a minimum safety factor of 2.0 to be verified during static pile load testing operations.

b. The allowable and ultimate tension capacities shall be 90 kips and 180 kips, respectively.

2. The required pile capacities shall be verified by testing as specified herein and in SECTION 310916.23.

C. Contractor and/or Subcontractor shall visit the site prior to mobilization of equipment to the site to observe and review specific site conditions, access and headroom conditions, requirements for equipment, and to evaluate methods and costs to install piling.

D. Related Work Specified Elsewhere:

1. Micropile Load Test - Static Axial Compression: SECTION

310916.23.

1.02 REFERENCES:

A. Applicable Standards:

1. American Concrete Institute (ACI):

a. ACI 305 - Hot Weather Concreting.

b. ACI 306 - Cold Weather Concreting.

2. American Society for Testing and Materials (ASTM):

a. A53 - Pipe, Steel, Black and Hot-Dipped, Zinc-Coated Welded and Seamless.

b. A252 - Welded and Seamless Steel Pipe Piles.

c. A615 - Deformed and Plain Billet-Steel Bars for Concrete

Reinforcement.

d. A722 - Uncoated High-Strength Steel Bar for Prestressing

Concrete.

e. C33 - Concrete Aggregates.

f. C109 - Test Method Compressive Strength of Hydraulic Cement

Mortars (Using 2 inch or 5 cm Cube Specimens).

g. C125 - Definitions of Terms Relating to Concrete and Concrete

Aggregates.

h. C150 - Portland Cement.

i. C618 - Fly Ash and Raw or Calcined Natural Pozzolan for Use as a Mineral Admixture in Portland Cement Concrete.

j. C937 - Grout Fluidifier for Preplaced-Aggregate Concrete.

3. Corps of Engineers:

a. CRD-C 611. Test Method for Flow of Grout Mixtures (Flow Cone

Method).

b. CRD-C 612. Test Method for Water Retentivity of Grout

Mixtures.

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c. CRD-C 613. Method of Test for Expansion of Grout Mixtures.

d. CRD-C 614. Method of Test for Time of Setting of Grout

Mixtures.

e. CRD-C 615. Method of Selecting Proportions for Intrusion Grout

Mixtures.

f. CRD-C 616. Test Method for Compressive Strength of Grout

Fluidifier Test Mortars.

g. CRD-C 619. Corps of Engineers Specifications for Grout

Fluidifier.

h. CRD-C 620. Standard Method of Sampling Fresh Grout.

4. Federal Highway Administration:

a. FHWA NHI-05-039. Micropile Design and Construction Reference

Manual.

1.03 EXPERIENCE QUALIFICATIONS:

A. A minimum of 5 years experience in micropile design and construction, including experience with similar subsurface materials, water conditions, micropile dimensions, and special techniques as required.

B. Submit a written description of equipment and techniques proposed for use on this Contract, and the name of five similar projects successfully completed in the last 2 years. A brief description of each project and a reference shall be included for each project listed. As a minimum, the reference shall include an individual’s name and current phone number.

C. Contractor shall assign a registered Professional Engineer to perform final design of the micropiles, evaluation of load tests, and to supervise all aspects of the Project, with at least three years of experience in the design and construction of micropiles. The use of manufacturers’ representatives does not satisfy the requirements of this section.

D. Drill operators and on-site supervisors shall have a minimum of one year experience installing micropiles with Contractor’s organization.

E. The experience statement of past work and description of equipment and techniques proposed for use shall be submitted at time of Bid and will be considered in the evaluation of bids. Engineer will approve or reject Contractor’s qualifications and staff within 15 working days after receipt of the submission. Work shall not be started on any piling nor materials ordered until approval of Contractor’s qualifications are given. Engineer may suspend the micropile work if Contractor substitutes unqualified personnel for approved personnel during construction. If work is suspended due to the substitution of unqualified personnel, Contractor shall be liable for additional costs resulting from the suspension of work and no adjustment in contract time resulting from the suspension of work will be allowed.

F. All other guidelines for submitting Subcontractor information shall be followed in accordance with that specified in "INSTRUCTIONS TO

BIDDERS".

1.04 DESIGN CRITERIA:

A. The micropiles shall be designed to meet the requirements of IBC 2006 and the FHWA Micropile Design and Construction Reference Manual (Publication No. FHWA NHI-05-039).

B. Minimum steel casing diameter of 7.625 inches.

C. Minimum steel casing wall thickness of 0.430 inch.

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D. For permanent steel casing used as reinforcing, design stress analysis shall consider a reduction in the outside diameter of steel pipe by 0.4-inch to allow for 0.2-inch steel thickness corrosion.

E. Minimum rock socket diameter of 7.5 inches.

F. Minimum rock socket length as indicated on Drawings, or as deemed appropriate pending results of static pile load testing.

G. Minimum factor of safety for soil to pile bond shall be 2.0.

H. All new piling shall be 3 diameters or 36 inches away from existing or adjacent new piles, whichever is greater.

I. Total settlement under the applied design loading shall not exceed

1/2-inch under normal loading conditions.

J. The final length of the production micropiles shall be determined such that the required geotechnical capacity is developed by skin friction between the grout and soil over a suitable length in an appropriate bearing stratum (bond zone).

1.05 SUBMITTALS AND CONSTRUCTION RECORDS:

A. Submit as specified in DIVISION 1.

B. Submittals:

1. The Contractor’s Engineer shall submit structural and geotechnical design notes for the proposed micropile foundation system, signed and sealed by a Professional Engineer licensed in the State where the Work is performed. As a minimum, the micropile design calculations shall include the following:

a. Detailed summary of design assumptions.

b. Details of proposed micropile section(s), cased and uncased.

c. Micropile Design Axial Capacity Calculations, addressing both geotechnical and structural capacities of the micropile elements.

d. Combined Stress Calculations for cased section, cased section at threaded joints, and uncased section.

e. Bearing and tension plate calculations.

2. Proposed equipment and techniques for micropile installation, including rig name, model number, proposed earth and rock auger attachments, and proposed special equipment for proposed installation method.

3. Contractor shall submit detailed information about the proposed grout mix to Engineer a minimum of 14 calendar days prior to micropile installation. The information shall include:

a. Mix proportions and evidence that proposed mix provides adequate strength and uniform consistency of grout.

b. Type, manufacturer and chemical composition of grout.

c. Type, manufacturer or source, and purpose of admixtures.

d. Gradation, fineness modulus and source of fine aggregates

(where applicable).

e. Certification of grout mix materials to be in compliance with

"Applicable Standards," including cement, aggregate and all admixtures.

4. Proposed procedures for each anticipated method of construction -dry and cased, wet and cased, or other procedure including:

a. Detailed sequence of excavation and steel casing installation, water flushing, reinforcing steel placement, and grout injection.

b. Methods to prevent caving, if necessary.

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c. Procedures for supporting and centering reinforcing steel and steel casing during grout placement.

C. Construction Records:

1. Micropile Load Test Records - as specified in SECTIONS 310916.23 and 310916.24.

2. Daily Records: Contractor shall submit at the completion of each day, preliminary micropile installation logs containing the following information, where applicable.

a. Identification number.

b. Micropile dimensions.

c. Ground surface elevation.

d. Bottom of grout elevation.

e. Top of grout elevation.

f. Description of soils and rock encountered during drilling.

g. Bearing stratum description.

h. Nature and location of obstructions.

i. Water conditions during drilling and grout placement.

j. Amount of rock excavation and length of rock socket.

k. Date and time of water flushing.

l. Date and time of grouting.

m. Amount of grout used.

n. Grout head at surface.

o. Remarks concerning installation of micropile.

3. As-Constructed Records – Contractor shall submit within 30 calendar days after completion of the micropile work a report containing:

a. "As-constructed" drawings showing the location of the micropiles and pile lengths.

b. Steel manufacturer’s mill test reports for the steel pile components incorporated in the installation.

c. Final micropile installation logs (per Article 1.05.C.2, this

SECTION).

d. Grouting records indicating the quantity injected.

1.06 SUBSURFACE INFORMATION:

A. Subsurface information has been obtained at the Site of the Project.

B. There is no express or implied guarantee as to the accuracy or completeness of the subsurface information, nor of the interpretation thereof by the Owner, the Engineer, or any of their representatives.

C. The subsurface information or copies thereof do not form a part of this or any contract document issued by the Owner or Engineer.

D. In the event that additional subsurface information is required by the Contractor for final foundation design, the Contractor may obtain the services of a Geotechnical Engineer to perform a supplemental subsurface investigation and laboratory testing program and to prepare a Geotechnical Engineering Report.

PART 2 - PRODUCTS

2.01 STEEL CASING:

A. Steel casing shall conform to ASTM A252, Grade 3.

B. Minimum yield strength of steel casing shall be 80,000 lb/in2.

C. Minimum diameter of steel casing shall be 7-5/8 inches.

D. Minimum wall thickness of steel casing shall be 0.430 inch.

E. The steel casing tip shall be open-ended.

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F. Store steel casing on platforms, skids, or other supports at the Site and support to prevent excessive deflection.

2.02 REINFORCING STEEL:

A. Reinforcing steel shall conform to ASTM A615 (Grade 75) or ASTM A722

(Grade 150).

B. Reinforcing steel shall be installed as shown on the Contract

Drawings.

C. Reinforcing steel shall have non-corrosive centralizers installed a minimum of every 10 feet. In addition, the top centralizer shall be located within 5 feet of the top of the micropile and the lower centralizer shall be located not more than 1 foot above the bottom of the reinforcing bar.

D. Centralizers shall be fabricated from plastic or material that is non-detrimental to the reinforcing steel.

2.03 GROUT:

A. Cement-based grout shall consist of the following mixture so proportioned to produce a hardened mortar with a minimum compressive strength in 28 days of 4,000 psi or greater as determined by Contractor’s design, a water-cement ratio of 0.4 to 0.5, and as referenced to ASTM C125.

1. Portland Cement: Type I, II, or III conforming to ASTM C150.

2. Special Pozzolan: Use a special pozzolan consisting of a finely powdered siliceous material and conforming to the ASTM C618.

3. Grouting Agent: Use a grouting agent that will reduce the mixing water requirements of the cement mortar, retard the setting time, decrease bleeding, eliminate setting shrinkage, increase fluidity, and conform to the Corps of Engineers Specifications

CRD-C 611, CRD-C 612, CRD-C 613, CRD-C 614, CRD-C 615, CRD-C 616,

CRD-C 619, CRD-C 620, and ASTM C937.

4. Water: Use fresh clean water free from injurious amounts of sewage, oil, acid, alkali, and organic matter.

5. Fine aggregate:

a. Meet the requirements of ASTM C33.

b. Consist of clean, natural sand or of hard, dense, durable, uncoated rock particles and be free from injurious amounts of silt, loam, lumps, soft or flaky particles, shale, alkali, organic matter, mica, chert and other deleterious substances.

c. Be well graded from coarse-to-fine, with a fineness modulus between 1.40 and 3.40.

d. Fine aggregate will only be allowed in special situations (e.g., presence of large voids in the ground) as approved by the Engineer.

6. Mixing:

a. Mix the cement grout with approved equipment and accurately measure all materials by volume or weight. The grouting equipment shall produce a colloidially mixed grout free of lumps and undispersed cement. The grouting equipment shall be sized to enable the grout to be pumped in one continuous operation. The mixer shall be capable of continuous agitation of the grout.

b. Mixing time shall not be less than one minute producing a homogeneous grout having a consistency ranging between 16 and 35 seconds for a 1/2-inch opening (10 and 25 seconds for a

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3/4-inch opening) when tested with a flow cone in accordance with the Corps of Engineers’ Specification CRD-C 611. Perform flow cone test at least once for each truckload of grout, or as otherwise directed by Engineer.

c. The grout shall have a maximum temperature during placement of 95ºF.

d. Place grout within 45 minutes after mixing. This period may be extended to 90 minutes or longer as approved by Engineer.

7. Pumping:

a. Use approved pumping equipment having a screen no larger than

3/8-inch mesh between mixer and pump having a working pressure gauge in clear view of the operator.

b. Calibration of the pump shall be performed in the field prior to installation of micropiles with Engineer present to observe. Grout shall be placed into the hopper and pumped through the line into a large container of known volume; i.e., a barrel or 55-gallon drum. Similar calibration of the pump stroke rate shall be performed at the request of Engineer if Contractor changes or varies equipment or should volumes of grout take calculated during grout placement become suspect due to variations in calculated quantities or due to pump missing complete strokes.

8. Cement Grout Compression Tests:

a. A qualified testing laboratory shall be retained and compensated by Contractor to perform required grout compression tests.

b. Contractor shall obtain and furnish cube molds and cubes (2 inches x 2 inches x 2 inches) for testing in accordance with the provisions of CRD-C 620 and ASTM C109, respectively.

c. Furnish to the testing laboratory six test cubes for each 4 yards of grout placed with a minimum of six cubes for each day’s placement. Engineer may revise this frequency of obtaining and furnishing grout cubes throughout the course of construction, contingent upon Contractor providing substantiated evidence of adequate strength and uniform consistency of grout. Evidence may consist of either previous job performance records and submittals by the grout supplier or statistical demonstration of grout strength based upon laboratory test results from micropiles installed during construction. Provided evidence is demonstrated, when grout placement exceeds 16 yards per day, Engineer may reduce frequency to a minimum number of cubes not less than two sets of six test cubes per day, to be obtained at the discretion of Engineer and generally representing one set of morning and one set of afternoon installation activities.

d. Two cubes shall be tested in compression at each of the ages of 7 days, 28 days, and two retained for testing at 56 days, if the need is so determined.

PART 3 - EXECUTION

3.01 INSTALLATION:

A. Installation of micropiles shall only be performed in the presence of

Contractor's Geotechnical Engineer.

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B. Install in general accordance with FHWA NHI-05-039 Micropile Design and Construction Reference Manual.

C. Place the micropiles using core drilling, rotary drilling, percussion drilling, auger drilling, or other acceptable means to the specified micropile tip elevation or penetration, achieving required penetration into the medium to dense sand underlying the site.

D. Sequence of permanent casing installation, drilling of bond zone, grout injection, central reinforcing steel bar placement, and removal of temporary casing operations used for production piles shall be consistent with the sequence used for test pile installation operations.

E. If Contractor elects to use drilling fluid to maintain stability of borehole during production micropile installation operations, it shall be consistent with the type and dosage of drilling fluid utilized for the installation of the test micropiles.

F. Place micropiles without excessive duration or delay in one continuous operation to the required cutoff elevation, so as to preclude the possibility of grout setting up prior to the completion of micropile placement or cold joints forming in the micropile.

G. Contractor shall monitor the amount and rate of water and/or compressed air used during the pressure injection drilling.

H. Contractor shall use a neat cement grout or a sand-cement grout with a minimum 28-day unconfined compressive strength of 4,000 psi or higher as determined by the Contractor’s design requirements. The cement shall not contain lumps or other indications of hydration.

Admixtures, if used, shall be mixed in accordance with the manufacturer’s recommendations.

I. The grouting equipment shall produce a grout free of lumps and undispersed cement. The pump shall be equipped with a pressure gauge to monitor grout pressures. The grouting equipment shall be sized to enable the grout to be pumped in one continuous operation.

J. The grout shall be injected from the lowest point of the drill hole.

The grout may be pumped through grout tubes, casing, hollow-stem augers or drill rods. The quantity of the grout and the grout pressures shall be recorded. The grout pressures and grout takes shall be controlled to prevent excessive heave in cohesive soils or fracturing of rock formations. The entire micropile shall be filled with grout.

K. Upon completion of grouting, the grout tube may remain in the hole but it shall be filled with grout.

L. If grout loss or a drop in the grout level is observed after grouting and prior to the placement of steel casing, the grout will be allowed to cure for one day. The hole will then be re-drilled and re-grouted.

This process will be repeated until no grout loss or drop in the grout level is observed after grouting and prior to the placement of steel casing.

M. Provide hot weather protection to grout mix, installation equipment during placement, and fresh grout during curing in conformance to ACI 305, or as directed by Engineer.

N. Provide cold weather protection to grout mix and installation equipment during placement to prevent installation of frozen grout.

O. Provide cold weather protection to all exposed surfaces of fresh grout during curing in conformance to ACI 306, or as directed by Engineer.

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3.02 MICROPILE PENETRATION:

A. Micropiles shall be penetrate into and bear on the coral and coralline sandstone deposits underlying the Site. Static micropile load testing performed by the Contractor shall confirm final bond zone embedment depths required for the micropile foundations to achieve the required capacities with the minimum required factors of safety.

3.03 INSTALLATION TOLERANCE:

A. Micropiles shall not exceed a variation from the vertical of more than

1/4-inch per foot of pile length.

B. The center of the micropile head shall not vary from plan location at cutoff by more than 3 inches.

C. Acceptable tolerance of top of micropile from indicated cutoff elevation shall not be more than 1/2-inch. Contractor may elect to trim micropiles to cutoff elevation after the pile cap is excavated.

3.04 REJECTED PILES:

A. Engineer will determine the acceptability of all micropiles placed and may reject those piles which do not conform to the Contract Documents.

B. As directed by Engineer, for those micropiles which have been rejected, micropile shall either be left in-place, or cut off; and then install one or more new micropiles at locations designated by Engineer to replace the rejected pile and maintain symmetry of the pile group or cluster.

3.05 LOAD TESTS:

A. Contractor shall be required to install one (1) test micropile at locations selected by the Contractor and approved by the Engineer for load testing. All micropiles used during load tests, including test micropiles and reaction piles shall be considered waste piles and shall not be installed in production micropile locations.

B. Load tests shall be performed in a sequence which will promote conformance to schedule requirements. Contractor shall have load test framing, beams, and tiedown equipment available to prepare setups for all required test locations at the same time. Load test will be performed one at a time in sequence. Provide load cell, jacks, and required strain dial indicators, with adequate back-up equipment to perform one test at a time. Provide personnel to operate load test equipment throughout all required tests.

C. Production micropile installation shall not commence prior to completion of evaluation of load test results and subsequent approval of proposed production micropile lengths by the Engineer.

D. Test micropiles shall not be used for production piling after testing.

E. Axial compression load testing shall be performed in accordance with

SECTION 310916.23 - PILE LOAD TEST - STATIC AXIAL COMPRESSION.

3.06 PROOF TESTS

A. Perform proof tests on a minimum of 10 percent of the production micropiles. Production micropiles to be proof tested will be selected by the Engineer after the installation of all production micropiles.

B. The Contractor shall furnish materials, equipment and tools necessary to perform the proof tests, The Engineer will be present only to observe the performance of the proof tests by the Contractor.

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C. Perform the proof tests by incrementally loading the micropile to be tested in accordance with the following loading schedule:

Proof Test Loading Schedule 0.05P 0.25P 0.50P 0.75P 1.00P 1.25P 1.33P Where P = Allowable Compression Capacity

D. Except at the maximum proof test load, increase the loads from one increment to the next immediately after recording the micropile movement. Measure and record the micropile movement at the top of the pile for each load increment to the nearest 0.001 inches with respect to a constant elevation benchmark located sufficiently far away from the pile being tested so as not to be affected by the test. Monitor the load with a load cell. At the load increments other than the maximum test load, hold the load just long enough to measure the micropile movement, but the hold time does not need to be more than one minute. Hole the maximum test load for fifteen (15) minutes.

Periodically pump the jack as necessary to maintain a constant load.

Start the load holding period as soon as the maximum load has been applied and record the micropile movement at 1, 2, 3, 4, 5, 6, and 10 minutes.

E. If the micropile movement between the one (1) minute and ten (10) minute readings exceed 0.04 inches, hold the maximum test load for an additional 50 minutes and continue to record the micropile movements at 15, 20, 25, 30, 40, 50, and 60 minutes (measured from the commencement of the proof test).

F. Submit the results of the micropile proof testing within two (2) workdays of the completion of each test. Include a plot of micropile movements versus load with the test data.

G. Proof testing of micropiles with the ten (10) minute load-holding period is acceptable if the total movement measured between one minute and ten (10) minutes is less than 0.04 inches.

H. Proof testing of microppiles with sixty (60) minutes load-holding periods is acceptable if the creep rate does not exceed 0.08 inches per log cycle of time.

I. If a micropile fails the proof testing, the Contractor shall modify his design and/or installation procedures to provide micropiles with acceptable results. Any modifications to the micropile design and construction will be at the Contractor’s expense. Additional micropile(s) and/or proof tests required due to failed proof tests will be at the Contractor’s expense.

END OF SECTION 316333