Geotechnical Engineering Circular No. 9 Design, Analysis, and Testing of Laterally Loaded Deep Foundations that Support Transportation Facilities
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- 13.2 CONSTRUCTABILITY REVIEW
| 13 CONSTRUCTION CONSIDERATIONS 13.1 CONSTRUCTION MANAGEMENT AND INSPECTION Successful construction of foundation elements to meet the design objectives for lateral load resistance depends on a) achieving the predetermined minimum embedment established by the designer, b) avoiding disturbance of the geo-materials around the foundation element that are relied upon for providing resistance to lateral loads, and c) constructing the foundation elements with the required structural strength and integrity. Knowledgeable supervision and inspection is essential, and equally important is the recognition of, and response to, unanticipated site conditions that could adversely impact the performance of the foundation to lateral loading. Inspection roles and responsibilities are discussed in detail in Hannigan et al. (2016) and Brown et al. (2010) for driven piles and drilled shafts, respectively. Construction management and inspection considerations with specific bearing upon laterally loaded foundations are discussed in the following sections of this chapter. 13.2 CONSTRUCTABILITY REVIEW Prior to construction, the design should be reviewed to verify that the design is constructible with available means and methods. Elements of construction that may pose risks should be identified and mitigated if possible. Considerations fora constructability review may include 1. Are the foundation size and type appropriate a. Are pile sizes and lengths appropriate for the type of pile (diameter or dimension, steel section, steel thickness, etc Will piles require splicing and will that impact the schedule b. Are drilled shaft diameters reasonable given the project size and expected contractor pool Large diameter shafts maybe inappropriate on relatively small local projects that will only attract local contractors. 2. Can foundations of this size and depth be installed given the site constraints, such as working area, slopes, headroom, access, equipment support, etc 3. Can the proposed depths be realized, i.e., can the bearing strata be penetrated to the required depth with the proposed deep foundation size and type Are there risks of obstructions, rock, or other impediments to reaching the design length or otherwise installing the proposed foundation size and length a. For driven piles, a driveability analysis should generally be performed. b. For drilled shafts, the need to change tools or use specialty tools to penetrate hard layers or remove obstructions should be considered. 4. Are there risks regarding installation such as settlement due to vibration, soil instability in excavations drilled shafts, CFAs), contaminated spoils, etc 5. Are there risks to third parties, risks of damage to nearby structures, risks of public complaints or community impacts, etc 6. What will the construction sequence be and is it feasible (both technically feasible as well as economically feasible 198 7. If load tests are required, is there an area to perform such tests that is also representative of the subsurface conditions of the site as a whole (for applicability to the production piles/shafts). 8. If there are potential risks or foreseeable problems, are there ways to effectively and efficiently resolve issues related to those risks should they occur 9. If there is more than one viable alternative, develop cost estimates and consider constructability for comparison. The lowest cost alternative is not necessarily the best, especially if there is a higher risk potential associated with this alternative if the potential problem occurs during construction, the cost of the apparent lower cost alternative may increase significantly and may end up being well above the cost of the other, lower risk alternative. Constructability considerations will vary by project size, location, local conditions, local practice, and other aspects of the project. The list above is intended to provide some examples, but it is by no means expected to be a comprehensive list fora complete constructability review. Such a review should be performed by staff with appropriate construction experience. Download 6.03 Mb. Share with your friends:
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