ASTM D4945-08
Standard Test Method for High-Strain Dynamic Testing of Piles
- Standard No.
- ASTM D4945-08
- Release Date
- 2008
- Published By
- American Society for Testing and Materials (ASTM)
- Status
- Replace By
- ASTM D4945-12
- Latest
- ASTM D4945-17
- Scope
Based on the measurements from strain or force, and acceleration, velocity, or displacement transducers, this test method obtains the force and velocity induced in a pile during an axial impact event (see Figs. 1 and 2). The Engineer may analyze the acquired data using engineering principles and judgment to evaluate the integrity of the pile, the performance of the impact system, and the maximum compressive and tensile stresses occurring in the pile.
If sufficient axial movement occurs during the impact event, and after assessing the resulting dynamic soil response along the side and bottom of the pile, the Engineer may analyze the results of a high-strain dynamic test to estimate the ultimate axial static compression capacity (see Note 1). Factors that may affect the axial static capacity estimated from dynamic tests include, but are not limited to the: (1) pile installation equipment and procedures, (2) elapsed time since initial installation, (3) pile material properties and dimensions, (4) type, density, strength, stratification, and saturation of the soil, or rock, or both adjacent to and beneath the pile, (5) quality or type of dynamic test data, (6) foundation settlement, (7) analysis method, and (8) engineering judgment and experience. If the Engineer does not have adequate previous experience with these factors, and with the analysis of dynamic test data, then a static load test carried out according to Test Method D 1143
should be used to verify estimates of static capacity and its distribution along the pile length. Test Method D 1143 provides a direct and more reliable measurement of static capacity. Note 18212;The analysis of a dynamic test will under predict the ultimate axial static compression capacity if the pile movement during the impact event is too small. The Engineer should determine how the size and shape of the pile, and the properties of the soil or rock beneath and adjacent to the pile, affect the amount of movement required to fully mobilize the static capacity. A permanent net penetration of as little as 2 mm per impact may indicate that sufficient movement has occurred during the impact event to fully mobilize the capacity. However, high displacement driven piles may require greater movement to avoid under predicting the static capacity, and cast-in-place piles often require a larger cumulative permanent net penetration for a series of test blows to fully mobilize the capacity. Static capacity may also decrease or increase over time after the pile installation, and both static and dynamic tests represent the capacity at the time of the respective test. Correlations between measured ultimate axial static compression capacity and dynamic test estimates generally improve when using dynamic restrike tests that account for soil strength changes with time (see 6.8).
Note 28212;Although interpretation of the dynamic test analysis may provide an estimate of the pile''s tension (uplift) capacity, users of this standard are cautioned to interpret conservatively the side resistance estimated from analysis of a single dynamic measurement location, and to avoid tension capacity estimates altogether for piles with less than 10 m embedded length. (Additional transducers embedded near the pile toe may also help improve tension capacity estimates.) If the Engineer does not have adequate previous experience for the specific site and pile type with the analysis of dynamic test data for tension capacity, then a static load test carried out according to Test Method D 3689
should be used to verify tension capac........
ASTM D4945-08 Referenced Document
- ASTM C469 Standard Test Method for Static Modulus of Elasticity and Poisson''s Ratio of Concrete in Compression
- ASTM D198 Standard Test Methods of Static Tests of Lumber in Structural Sizes
- ASTM D3689 Standard Test Method for Individual Piles Under Static Axial Tensile Load (Withdrawn 2005)
- ASTM D3740 Standard Practice for Minimum Requirements for Agencies Engaged in the Testing and/or Inspection of Soil and Rock as Used in Engineering Design and Construction
- ASTM D6026 Standard Practice for Using Significant Digits in Geotechnical Data
- ASTM D653 Standard Terminology Relating to Soil, Rock, and Contained Fluids
ASTM D4945-08 history
- 2017 ASTM D4945-17 Standard Test Method for High-Strain Dynamic Testing of Deep Foundations
- 2012 ASTM D4945-12 Standard Test Method for High-Strain Dynamic Testing of Deep Foundations
- 2008 ASTM D4945-08 Standard Test Method for High-Strain Dynamic Testing of Piles
- 2000 ASTM D4945-00 Standard Test Method for High-Strain Dynamic Testing of Piles
