Geotechnical Engineering Circular No. 9 Design, Analysis, and Testing of Laterally Loaded Deep Foundations that Support Transportation Facilities
Considerations for Test Pile Installation Methods
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| 12.1.6 Considerations for Test Pile Installation Methods Ideally, the test piles/shafts should be installed using the same or similar means and methods for construction that are anticipated or required for the production piles/shafts. It is especially important to use methods for the test elements that will result in similar disturbance or lack thereof in the immediate area around the pile/shaft as compared to the production piles/shafts. For example, the installation of driven piles may result in a densification of the soils in the immediate vicinity of the pile pre-drilling of test piles should be avoided unless predrilling is also required for the production piles. Similarly, the use of oversized surface casing fora drilled test shaft should be avoided unless such measures are intended for the production shafts as well. During a design-phase test program, it may not be possible to anticipate and use the same means and methods for installation of the test elements as will be used during the subsequent construction contract. Similarly, if the testis performed early in a design-build contract, before the construction contractor finalizes his means and methods, there maybe some inconsistency between installation of the test pile/shaft and production piles/shafts. The methods for lateral pile analyses do not account for different installation methods, but it is known that installation means and methods can have a significant influence on the test results. If the designer is comfortable that different methods will not compromise or alter the behavior of the subsurface materials under lateral loads, the data from the tests should be applicable. However, if, in the judgment of the designer, there exists some risk that the production pile/shaft behavior under lateral loads maybe different than the test pile/shaft due to differences in the installation methods, it maybe desirable to defer the test program until the means and methods of construction are defined, or plan the test program to model the likely more adverse condition that maybe used in construction, or include more restrictive limits to the contractor’s means and methods in the contract specifications. |