38 NOVEMBER 2025 WorldWide Drilling Resource® Seismic Engineering Challenges for an International Airport Adapted from Information by Kleinfelder The expansion of Terminal One (T1) at San Diego International Airport in California, represents a significant infrastructure development for the area, featuring a new terminal building, a large parking garage, and an extensive network of access roads. The access road system will consist of nine bridges, various retaining walls, and both ground-level and elevated roadways. The design-build initiative is spearheaded by a joint venture between Turner and Flatiron, with Gensler serving as the lead architect and Kleinfelder acting as the civil engineer for landside and geotechnical engineering on both airside and landside. Kleinfelder collaborated with Turner Engineering Group to optimize design and mitigate risks associated with site challenges. The project’s complexity is underscored by its proximity to the Rose Canyon Fault Zone (RCFZ). While not as notorious as the San Andreas Fault, historical seismic activity and recent research indicate RCFZ is capable of generating significant earthquakes, potentially reaching a magnitude of 7.0 or greater. Additionally, the airport’s location on hydraulically filled reclaimed land adjacent to San Diego Bay leads to shallow groundwater and loose, compressible soil conditions that could liquefy, weaken, and settle during a major seismic event. Given these geological and seismic conditions, innovative earthquake engineering solutions were essential to ensure the safety and durability of the project’s structures. A thorough geotechnical investigation was crucial to evaluate the seismic risks linked to the terminal, parking garage, and access roads. Four main seismic factors influenced the design of T1 and its infrastructure: liquefaction, lateral spreading, seismic ground motions, and fault rupture. To tackle the four seismic challenges identified at the project site, the following strategies were implemented. For seismic support, deep foundations utilizing Auger Cast-in-Place (ACP) piles were employed for the T1 building and parking garage, while Cast-in-Drilled-Hole (CIDH) piles were utilized for the bridge structure. ACP piles are deep, cast-inplace column elements created with a hollow stem auger that pumps grout from the bottom of the drilled hole as the auger is extracted, reinforced with a steel cage. CIDH piles are large-diameter, high-capacity columns that involve pumping grout into an open drilled hole supported by polymer slurry or casings. These foundations extend well below the loose and soft liquefiable soil layers, designed to resist both structural and seismic loads from liquefaction and lateral spreading. Ground improvement methods were applied at specific bridge approaches and retaining walls to counteract the potential for seismic slope instability. Techniques such as DSM (deep soil mixing), which injects high-pressure columns of grout into the ground, were implemented to ensure ground stability without extensive reinforcements. These methods provided a costeffective solution while meeting seismic resilience requirements. To address the surface fault rupture hazard, the eastern edge of the T1 building was designed to maintain a minimum distance of 25 feet from the active strands of the RCFZ, resulting in an angled design for the eastern end of the structure. The strategies employed throughout the design and construction phases offer important lessons for future airport projects across the country. The expansion of T1 at San Diego International Airport stands as a remarkable engineering accomplishment, adeptly addressing substantial seismic challenges to accommodate the increasing demand for air travel while enhancing the airport’s infrastructure. By utilizing site-specific seismic analyses, deep foundation systems, and cutting-edge ground improvement methods, the geotechnical engineers on the design-build team provided economically viable solutions for the new terminal, bridges, and access roadways that are resilient to earthquake risks inherent to the region. GEOTECH The 2026 Marketing Guides are headed your way ~ Plan your 2026 advertising campaign today! Call for more information 850-547-0102 worldwidedrillingresource.com
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