1、418SECTION 700 STRUCTURESSECTION 701 DRIVEN PILING701.01 Description. This work shall consist of furnishing and driving foundation piles of the type and dimensions designated including cutting off or building up foundation piles when required. Piling shall conform to and be installed at the location
2、, tip elevation, penetration, or bearing in accordance with 105.03.MATERIALS701.02 Materials. Materials shall be in accordance with the following:Epoxy Coating for Piles .915.01(d)Reinforcing Steel910.01Steel Encased Concrete Piles .915.01Steel H Piles .915.02Structural Concrete.702Timber Piling, Tr
3、eated .911.02(c)Timber Piling, Untreated911.01(e)Reinforcing steel within steel shell piles and in the reinforced concrete pile encasement shall not be epoxy coated.Powdered epoxy resin shall be used to coat the epoxy coated portion of the steel shell encased concrete piles.The Contractor may furnis
4、h and drive thicker walled steel shells than specified.701.03 Handling of Epoxy Coated Piles. Piles shall be shipped using dunnage and padding shall be used with chains or steel bands.Damage to epoxy coated piles shall be repaired in accordance with 915.01(d). Epoxy coated piles will be rejected if
5、the total area of repair to the coating exceeds 2% of the total coated surface area.CONSTRUCTION REQUIREMENTS701.04 Equipment for Driving Piles.(a) Approval of Pile Driving Equipment. All pile driving equipment furnished by the Contractor shall be in working condition and subject to approval. All pi
6、le driving equipment shall be sized such that the piles can be driven with reasonable effort to the ordered lengths without damage. The pile driving equipment shall not be used until approval is received in writing. The Contractor shall submit to the Geotechnical Engineer, Materials and Tests Divisi
7、on, with a copy to the Engineer, a completed Pile and Driving Equipment Data Form at least 15 calendar days prior to driving piles. The form will be included in the Proposal book. Pile driving equipment will be subject to satisfactory performance during production.419The Engineer will use the inform
8、ation provided by the Contractor to run the wave equation analysis or the alternate method, from which the acceptance of the pile driving equipment will be founded. Approval criteria of pile driving systems will consist of both the required number of hammer blows per meter (foot) and the pile stress
9、es at the required pile capacity. The required number of hammer blows indicated by the wave equation at the ultimate pile load shall be less than 600 blows per meter (180 blows per foot) for the pile driving equipment to be acceptable.1. Wave Equation Analysis Method. For the pile driving equipment
10、to be acceptable, the driving stresses predicted by the wave equation analysis shall not exceed the values where pile damage impends. These limiting values may be calculated as follows:a. The maximum allowable compressive and tensile stress for steel piles = 0.9Fy.b. The maximum allowable compressiv
11、e stress for prestressed concrete piles = 0.85fc - effective prestress.c. The maximum allowable tensile stress, MPa (psi), for prestressed concrete piles = 0.25 fc+ effective prestress, where fc is expressed in MPa (3fc+ effective prestress, where fc is expressed in psi).d. The effective prestress m
12、ay be obtained from the approved shop drawings.The Contractor will be notified of the acceptance of the proposed pile driving system within 15 calendar days of the receipt of the Pile and Driving Equipment Data Form. If the wave equation analysis shows that either pile damage or inability to reasona
13、bly drive a pile with respect to allowable blow counts will result from the proposed equipment, the Contractor shall modify or replace the proposed equipment until subsequent wave equation analyses indicate the piles can be reasonably driven to the desired ultimate capacity, without damage. The Engi
14、neer will notify the Contractor of the acceptance of the revised driving system within seven calendar days of receipt of a revised data form.No variation in the pile driving system will be permitted without written approval, with the exception of increasing concrete pile cushion thickness to control
15、 driving stresses. Changes in the driving system will only be considered after the Contractor has submitted the necessary information for a revised wave equation analysis. The Contractor will be notified of the acceptance of the pile driving system changes within three work days of the receipt of th
16、e requested change.2. Alternate Method. If the alternate method is used, the energy of the pile driving equipment shall be rated by the manufacturer at or above the appropriate minimum manufacturers rated hammer energy for the corresponding ultimate pile capacity as shown in the table below. The ult
17、imate pile capacity as shown on the plans is equal to the design load times the factor of safety.420ALTERNATE METHODMINIMUM PILE HAMMER REQUIREMENTSMinimum Manufacturers RatedUltimate Pile Capacity, Hammer Energy,Kilonewtons (Kips) Joules (Foot-pounds)450 and under (100 and under) 9 830 (7,250)451 t
18、o 800 (101 to 180) 12 200 (9,000)801 to 1330 (181 to 300) 20 340 (15,000)1331 and over (301 and over) wave equation requiredThe Contractor shall use the approved system and no variations in the driving system will be permitted without the Engineers approval. All changes in the pile driving system wi
19、ll only be considered after the Contractor has submitted a new Pile and Driving Equipment Data Form. The Contractor will be notified of the acceptance of the proposed change in driving equipment within three work days of receipt of the data form. If the Engineer determines the Contractors hammer is
20、not functioning properly and is unable to drive the pile to the required depth, the hammer shall be removed from service.(b) Pile Hammers. Concrete piles of 500 mm (20 in.) diameter or width and larger shall be driven by means of air, steam, diesel, or hydraulic hammers, unless otherwise approved. S
21、teel piles shall be driven with air, steam, diesel, or hydraulic hammers. Gravity hammers shall only be used if specifically permitted in the contract or approved in writing.1. Gravity Hammers. When gravity hammers are permitted, the ram shall have a mass (weight) of between 1360 and 1590 kg (3,000
22、and 3,500 lbs). The height of drop shall not exceed 4.5 m (15 ft). The mass (weight) of gravity hammers shall not be less than the combined mass (weight) of the drive head and pile. All gravity hammers shall be equipped with hammer guides to ensure concentric impact on the drive head.2. Steam and Ai
23、r Hammers. The plant and equipment furnished for steam and air hammers shall have sufficient capacity to maintain, under working conditions, the volume and pressure specified by the manufacturer of the hammer. The plant and equipment shall be equipped with accurate chamber pressure gauges which are
24、accessible to the Engineer. When wave equation analysis is not used for pre-approval, the weight of the striking parts of air and steam hammers shall not be less than one third the weight of the drive head and pile being driven. The striking parts shall not weigh less than 1250 kg (2,750 lbs).3. Die
25、sel Hammers. Open-end or single acting diesel hammers shall be equipped with a device such as rings on the ram, a scale, or a jump stick, extending above the ram cylinder, to permit the Engineer to visually determine hammer stroke at all times during pile driving operations. The Contractor shall pro
26、vide the Engineer a chart from the hammer manufacturer equating stroke, blows per minute, and potential energy for the open-end diesel hammer. Closed-end double acting diesel hammers shall be equipped with a bounce chamber pressure gauge, in working order, mounted near ground level so as to be read
27、by the Engineer.421The Contractor shall provide the Engineer a chart equating bounce chamber pressure to either equivalent energy or stroke for the closed-end diesel hammer to be used. This calibration to actual hammer performance shall be performed within 90 days before the beginning of the work.4.
28、 Pile Driving Aids. Pile driving aids such as jets, followers, and prebored holes shall not be used unless specified. If specified, pile driving aids shall be used for installing production piles only after the pile tip elevation for safe support of the pile load is established by means of load test
29、ing or test piles conventionally driven. The Contractor shall perform all extra load tests or extra work required to drive test piles as determined by the Engineer.(c) Pile Driving Appurtenance.1. Hammer Cushion. All impact pile driving equipment, except gravity hammers, shall be equipped with a sui
30、table thickness of hammer cushion material to prevent damage to the hammer or pile and to ensure uniform driving behavior. Hammer cushions shall be made of durable, manufactured materials, provided in accordance with the hammer manufacturers guidelines. All wood, wire rope, and asbestos hammer cushi
31、ons will not be permitted. A striker plate as recommended by the hammer manufacturer shall be placed on the hammer cushion to ensure uniform compression of the cushion material. The condition of the hammer cushion shall be checked with the Engineer at the beginning of pile driving and after each 100
32、 h of pile driving. A hammer cushion whose thickness has been reduced to less than 75% of the original thickness shall be replaced.2. Pile Drive Head. Piles driven with impact hammers shall have an adequate drive head to distribute the hammer blow to the pile head, be axially aligned with the hammer
33、 and the pile, be guided by the leads, and not be free-swinging. The drive head shall fit around the pile head and prevent transfer of torsional forces during driving while maintaining proper alignment of hammer and pile.For steel and timber piling, the pile heads shall be cut squarely.A drive head
34、as recommended by the manufacturer shall be provided to hold the axis of the pile in line with the axis of the hammer. The pile head shall be plane and perpendicular to the longitudinal axis of the pile to prevent eccentric impacts from the drive head.3. Pile Cushion. The heads of concrete piles sha
35、ll be protected with a pile cushion made of plywood. The minimum plywood thickness placed on the pile head prior to driving shall not be less than 100 mm (4 in.). A new pile cushion shall be provided for each pile. The pile cushion shall be replaced if, during the driving of the pile, the cushion is
36、 either compressed more than one-half the original thickness or begins to burn. The pile cushion dimensions shall equal or exceed the cross sectional area of the pile top, and shall be sized to fit the dimensions of the pile cap.4224. Leads. Piles shall be supported in line and position with leads w
37、hile being driven. Pile driver leads shall be constructed in a manner that affords freedom of movement of the hammer while maintaining alignment of the hammer and the pile to ensure concentric impact for each blow. Leads may be either fixed or swinging type. Swinging leads, when used, shall be fitte
38、d with a pile gate at the bottom of the leads. The leads shall be adequately embedded in the ground, or the pile shall be constrained in a structural frame such as a template to maintain alignment.5. Followers. Followers shall only be used when approved in writing by the Engineer. If a follower is p
39、ermitted, the first pile in each bent and every tenth pile driven thereafter shall be driven full length without a follower, to verify that adequate pile length is being attained to develop the desired pile capacity. The follower and pile shall be held and maintained in equal and proper alignment du
40、ring driving. The follower shall be of such material and dimensions to permit the piles to be driven to the length determined necessary from the driving of the full length piles. The final position and alignment of the first two piles installed with followers in each substructure unit shall not exce
41、ed more than 75 mm (3 in.) from the locations shown on the plans before additional piles are installed.6. Jets. Jetting will not be permitted for concrete piles unless otherwise specified. The Contractor shall determine the number of jets and the volume and pressure of water at the jet nozzles neces
42、sary to freely erode the material adjacent to the pile without affecting the lateral stability of the final in-place pile. The Contractor shall be responsible for all damage to the site caused by improper jetting operations. If jetting is specified, the jetting plant shall have sufficient capacity t
43、o permit installation to the required elevation, location, and alignment in accordance with 701.09(b). Unless otherwise directed, external jet pipes shall be removed when the pile tip is 3.0 m (10 ft) above the prescribed tip elevation, depending on soil conditions. The pile shall then be driven to
44、the required bearing capacity with an impact hammer. The Contractor shall control, treat if necessary, and dispose of all jet water in accordance with 108.03.Upon completion of driving a jetted pile, all voids around the pile shall be filled with B borrow and saturated with water.701.05 Test Piles.
45、Test piles shall be driven when shown on the plans at the locations and to the lengths specified or as directed by the Engineer. Unless otherwise directed, test piles shall be driven at such locations to permit their use in the finished structure. Test piles shall not be driven outside of permanent
46、pile locations and be pulled and redriven as production piles. Test piles specified to be used as permanent piles in a structure shall have sufficient length to be cut off at the plan grade for top of pile. The length of test piles shall be greater than the estimated length of production piles in or
47、der to provide for variation in soil conditions. Precast concrete and treated timber test piles shall be a minimum of 3.0 m (10 ft) longer than the estimated length of piling shown on the plans. Steel piles shall be provided such that additional 3.0 m (10 ft) of driving will not require an additiona
48、l splice.The driving equipment used for driving test piles shall be identical to that proposed for use on the production piling and shall be subject to approval. The 423Contractor shall excavate the ground at each test pile to the elevation of the bottom of the footing before the pile is driven, unl
49、ess shown on the plans or otherwise directed.Test piles shall be driven to the required pile capacity or as directed. Each test pile shall be restruck after a 24 to 72 h waiting period to assess the effects of setup and relaxation unless otherwise approved. The hammer shall be warmed up before driving begins by applying at least 20 blows to another fixed object. If the test pile does attain the specified capacity upon restriking, the blow count attained during initial driving shall be used to establish the adequacy of production piles. If the specified capacity is not attai
