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This standard is issued under the fixed designation D /D M; the 1 This test method is under the jurisdiction of ASTM Committee D18 on Soil and. 1 These test methods are under the jurisdiction of ASTM Committee D18 on Soil and Rock and are the direct Downloaded/printed by. Ali Qzaz () pursuant to. This standard is issued under the fixed designation D ; the number 1 This test method is under the jurisdiction of ASTM Committee D on Soil and Rock.
In the realm of load testing an assortment of test methods are available for foundations. Each methodology has is merits as such many issues play into the selection of the most appropriate method. These methods have historically been divided into two categories: static or dynamic. Recently a new classification of testing denoted as rapid load testing has emerged, which combines many of the benefits of the previous methods. Static load tests are thought to provide the most reliable results and the analysis is straightforward. However, the tests are costly and time consuming. Additionally, they are not immune to side effects such as influence from reaction piles, maintaining independent displacement measurements and precision of load measurement e.
Smooth bearing surfaces such as glass perpendicular to 4. Target rods shall cable from anchor piles or cribbing.
A minimum of two dial read to 0. The wire shall be not more than 1 in. A suitable method shall be used to maintain tension in the wires throughout the test so that when plucked or tapped, the wire will return to its original position.
Piano wire or equivalent type shall be used. Reference points or scales used in taking settlement readings shall be mounted on the sides of the test pile or pile cap and located on opposite sides except that reference points may be on top of the pile cap or readings may be taken on a single fixed point in the center of the test pile top, test plate or pile cap or on scales mounted on the test plate provided that relative movements between the test plate and the top of the pile are measured in accordance with 4.
Alternatively, the two pile or pile cap 90 apart with readings referenced to fixed dial gages shall be mounted on opposite sides of the test pile or foresights or backsights. For tests on batter piles, one of the pile cap below the test plate with stems parallel to the gages or scales shall be oriented in the direction of the batter.
However, gages may be 4. For terminating at the pile tip and at other points along the pile as tests on individual batter piles, the dial gages shall be mounted required and shall be sheathed or encased to insure free along a line perpendicular to the direction of batter.
The influence of the NOTE 10The use of four dial gages mounted 90 apart is recom- sheathing on the elastic properties of the pile section shall be mended to compensate for lateral movement or rotation of the pile butt considered.
If electric resistant strain gages are used, the gage due to accidental eccentric loading. The movements of the top of each strain rod direction that permits placing the wire supports as far as relative to the top of the test pile shall be measured with a dial practicable from anchor piles or cribbing. Each wire shall pass gage reading to 0. Dial gages shall be across and be clear of the face of a scale that is mounted referenced to points on the test pile below the test plate except parallel to the axis of the test pile or piles within the group and that they may be referenced to the top of the test plate if the that is attached to a mirror fixed to the test pile or pile cap so plate is welded to the pile or if relative movements between the that consistent readings of axial movement can be made top of the test pile and the test plate are measured in accordance 6 FIG.
If pile 5.
Loading Procedures failure occurs continue jacking the pile until the settlement 5. Maintain each removing load increments, tighten the wedges along the load increment until the rate of settlement is not greater than platform edges to stabilize the platform. Place or remove load 0. Provided that the increments in a manner which avoids impact and maintains the test pile or pile group has not failed, remove the total test load load balanced at all times.
After each load increment has been anytime after 12 h if the butt settlement over a one-hour period added, loosen but do not remove the wedges and keep them is not greater than 0. After the occurs. Such testing permits the selection of optimum pile type and at which time release the load.
If the pile stops penetrating design load. NOTE 14If the test pile s may exhibit or has exhibited negligible settlement at the design load or may approach or has approached incipient 5. After removing each increments of min or as otherwise specified. Apply additional loads in accordance is reached, whichever occurs first, at which time stop the with 5. After the total required test load has been applied, jacking. After a 5-min interval or as otherwise specified, hold and remove the test load in accordance with 5.
Then increase 5. If failure does not occur, hold 5. Vary the 5. Continue loading the pile 5. A mechanical After removing the first load decrement, do not remove pump equipped with a bleed valve, variable speed device, or additional decrements until the rate of pile rebound for the other means for providing a smooth variable delivery shall be preceding load decrement is less than 0.
If a video recording system is used to record the test data, diameter or diagonal dimension per hour. The waiting period will cohesive soil or 0. Continue loading the the soil properties. It could range from a minimum of 3 days to as long as pile until no further increase in the load is necessary for 30 days or longer and the actual required waiting period may be continuous pile penetration at the specified rate unless the determined by testing for example redriving piles or by prior experience.
If pile NOTE 17To avoid excessive creep of green concrete in cast-in-place penetration continues, hold the load required to achieve the concrete piles, the elapsed time between concrete placement and pile 8 D testing should be sufficient to permit the concrete to cure and harden Take readings of time, load, and settlement, and record properly, recognizing that the curing time for the concrete in the pile immediately before and after each settlement increment with generally will be longer than that for the sampled concrete in standard test sufficient intermediate readings so as to determine the rate of cylinders.
Procedures for Measuring Pile Movements settlement increment.
During unloading, take readings of time, load, and rebound, and record immediately before and after the 6. Take final provided that the requirements of 4. For lateral readings and record 12 h after all load has been removed. Take required readings at each properly identified gage, NOTE 19Level readings should be taken on the reference beams and scale, or reference point as nearly simultaneously as practi- on the reaction system using a surveyors level or transit and target rod or cable.
When using the loading method described in 3. Such readings should be taken and recorded before any test load is applied, at the the no-load reading before the test beam s and platform are proposed design load, at the maximum test load, and after all load has permitted to bear on the pile s.
Clearly indicate and explain been removed. Intermediate readings may be required if results during any adjustments made to instrumentation or to data recorded in testing appear unusual. NOTE 20When testing piles in granular soils in dewatered excava- 6. During loading, provided that the test pile or pile during the test. If the groundwater level during the test is more than 5 ft 1.
After the total load has 7. Safety Requirements been applied, provided that the test pile or pile group has not 7.
The following not exceeding 2 h for the next 12 h. If pile failure occurs, take safety rules are in addition to general safety requirements readings immediately before removing the first load decre- applicable to construction operations: ment.
During unloading, take readings and record at intervals not exceeding 20 min. Take a final rebound reading 12 h after 7.
NOTE 18If incremental strain measurements as in 4. If automatic monitoring and re- 7. When the test pile has achieved its specified rate of 7. Immediately after unloading, take and record readings factor of safety. Take final readings and record 1 h 7. When intermediate time intervals as specified. When the maximum using loading method in 3. During testing, jacking is stopped. Repeat after min and again at 5 min movements of the reaction load or system should be monitored thereafter.
If a longer holding period than in 5.
Methods of Selecting the Driving System Because different types diesel, air, hydraulic, etc. The minimum requirements for the driving system, usually requiring hammer energy, are developed by the design engi- neer and included in the project plans or called out from stan- dard specifications. Pile driving formulas or wave equation analysis are the most common methods for establishing the minimum required hammer energy.
Economics are a major consideration in the selection of the driving system by the contractor. For instance, hammer size can affect crane size requirements, and air or hydraulic hammers may require substantial support equipment compared with simpler diesel hammers. Productivity and schedule requirements are a major consideration to the contractor.
In the case of design-build project delivery, the design and construc- tion partners typically have additional economic incentive to work collaboratively to find the optimal pile driving system. Wave equation analysis is a common technique to evaluate drivability and productivity. Varying Types of Contractor Submittals Required for the Installation of Piles In most cases, the minimum required hammer energy is spec- ified in either the project plans or the standard specifications.
In such cases, the minimum contractor submittal for pile instal- lation is the proposed hammer and supporting equipment pile leads, power supply, cranes, etc. In some cases, particularly in the design-build project environment, a contractor-performed wave equation analysis is required to demonstrate that the hammer can drive the proposed piles to the correct resis- tance without damage.
Additional submittals can occasionally include installation sequence or procedure, procedures for test- ing or restrikes, and procedures for remediation of piles that are suspect or do not meet the planned driving criteria. Although restrikes or load tests may be performed after setup has occurred to document that the pile has the design resis- tance, the driving criteria are set for the conditions at the time of driving.
By reliably quantifying setup before or at the start of production pile driving, its effect can be factored into the driving criteria by determining an acceptable end of drive blow count that includes an allowance for the setup, or by establish- ing an acceptable end of drive resistance as measured by a PDA.
If setup is not accounted for, the criteria would be estab- lished for a pile resistance that cannot be achieved at the end of drive, causing delays, disputes, overruns in pile quantities, or excessive restrike tests to confirm that piles have the required resistance for the design.
Setup can be quantified based on local experience by a program of restrike measurements at a range of times after initial driving, by static load tests, or another systematic man- ner. With appropriate conservatism in setting pile tip eleva- tions, the risk of delays owing to questions regarding pile axial resistance and the need for set checks or splices can be reduced when setup is accounted for.
Piles driven to satisfy the estab- lished criteria that accounts for setup are assured to ultimately achieve the required axial resistance. Relaxation, or the loss of resistance over time, can also have an impact on driving criteria. Although relaxation is a rare occurrence, it needs to be considered in those soil and rock for- mations where it typically occurs.
Failure to account for relax- ation when it does occur results in nonconservative driving criteria. Methods of Determining the Number and Distribution of Pile Tests for Use in a Pile Testing Program The number and distribution of pile tests in a testing pro- gram can be selected either with a rigidly specified proce- dure or by guidelines that call for individual judgment of the project conditions. Rigid specifications often require that certain tests be performed at a specific interval. In design-build projects, economic and schedule decisions are significant influences, as are the potential to reduce uncer- tainty.
Sometimes the benefits of additional test piles, mani- fested in higher resistance factors, confirmation of driving system performance, or confirmation of setup can more than offset the additional cost for the test piles.
Site-specific SLTs may be used to correlate dynamic test results with static axial resistance to increase the reliabil- ity of dynamic test measurements. Varying Soil Conditions Across a Project and Its Effect on Driving Criteria Because soil conditions can often vary significantly across a site, the development of driving criteria can be impacted not only the by location of tests or observations for criteria devel- opment, but also by the frequency of tests on a site.
Where significant changes in soil type occur, different cri- teria need to be developed e. The presence of refusal driving con- ditions with an adequately sized hammer may vary signifi- cantly across the site, requiring differing criteria to cover areas of potential pile refusal and areas where piles will not achieve refusal. Piles driven to a driving resistance as determined by a PDA are often associated with a specific minimum blow count at the desired tip elevations.
The variation of soil strength estimated or measured for axial design, as well as the variation in ham- mer energy and efficiency, can mean that achieving something less than X blows per foot in a certain clay strata does not necessarily mean a pile does not provide the required resis- tance.
Although blow counts can be indicators, trying to achieve a certain blow count value of X can create difficulties if variations in soil strength are not taken into account. If only one test is done and the blow count is 10 blows per foot when the required resistance is met, then all piles will be subject to those criteria if an allowance for soil variation is not considered. Effects of Production Pile Driving Criteria on the Resistance Factor Chosen for Design The selection of production pile criteria can affect the design resistance factor through the methods used to determine the criteria.
The selection is based on the type and frequency of testing performed before and during produc- tion pile installation. In general, higher resistance factors are allowed as the frequency of testing increases, resulting in pos- itive effects on the design. If little or no verification testing is used to establish or confirm driving criteria or pile perfor- mance, the design is impacted by the requirement to utilize lower resistance factors. The first phase Phase I consisted of a written survey to all state geotechnical engineers or equivalent.