TECHNICAL ACTIVITIES New Co-Chair for Seepage Control Committee Join DFI in welcoming Gregg Batchelder Adams, P.E., U.S. Army Corps of Engineers (USACE), as the new co-chair of DFI's Seepage Control Committee. He joins Co- Chair Michael Kynett, P.E., MBK Engineers. Batchelder Adams has close to 40 years of experience in civil and geotechnical engineering. He is currently a lead civil engineer for the USACE Risk Management Center located in Colorado. Batchelder Adams has worked for a building contractor, a state highway agency, two globally focused engineering consulting firms, and for the U.S. Department of the Interior and Department of Defense. For the past 30 years, he has focused on the evaluation, inspection, design, construction and risk assessment of dams and levees throughout the U.S. and abroad. He has a Bachelor's COMMITTEE CHAIR JONATHAN HUFF, P.E. Augered Cast-in-Place and Drilled Displacement Pile Committee Considering Large-Diameter ACIP Piles Oftentimes in the design of deep foundations for a structure, a single deep foundation element is included under building columns. Perhaps the most commonly used single support element is a drilled shaft. However, with the continued advancement of drilling equipment capabilities, the use of a single, high-capacity, large-diameter augered cast-in-place (ACIP) pile is becoming more and more common. ACIP pile diameter capabilities have increased to as large as 48 in (122 cm), and often make for a highly effective single support element under a column. However, a commonly perceived roadblock in the design of these single ACIP pile supports is sometimes encountered: Is a single pile stable without lateral support from grade beams? The International Building Code (IBC) makes recommendations regarding the stability of deep foundations in Section 1810.2.2. The code states that “deep foundation elements shall be braced to provide lateral stability in all directions.” This can be done with the use of (a) grade beams, (b) pile groups under a cap, or (c) a single deep foundation element of sufficient diameter to be considered adequately braced on its own. The code further details the require- ments of option (c) by stating, “Isolated cast-in-place deep foundation elements without lateral bracing shall be permitted where the least horizontal dimension is no less than 2 ft (0.61 m), adequate lateral support in accordance with Section 1810.2.1 is provided for the entire height and the height does not exceed 12 times the least horizontal dimension.” Since ACIP piles are often quite long with respect to their diameter, some engineers will say, “Look! Your pile is longer than 12 times the diameter! You don't meet the requirements of the isolated deep foundation element! You have to use pile groups instead of a single pile.” This evaluation seems so perfectly counterintuitive. Is a pile somehow less stable laterally when it is drilled deeper than 12 times its diameter? Why did the code writers choose the word “height” instead of “length” or “depth”? Why are drilled shafts not held to this same requirement? In an effort to further understand this code requirement and ensure that deep foundations are designed in a manner that meets the intent of the building code, the ACIP/DD Pile Committee is performing research and will write a white paper on this topic. The paper is expected to be finalized in 2021, so stay tuned! Mary Ellen Bruce Large, P.E., D.GE Director of Technical Activities [email protected] degree in civil engineering from the University of Vermont and a Master's degree in civil engineering from the University of New Hampshire. DFI and federal and state agencies established the Seepage Control Committee as a collaborative forum to discuss industry best practices for seepage cutoff and foundation improvement of water infrastructure projects. The goals of the group are to promote mutual understanding of technologies, appropriate specification models, responsible contracting and procurement processes and effective quality assurance/control. This owner and practitioner group is aimed at improving communication, aligning expectations, and defining common goals to generate the ultimate benefits of improved safety and quality and reduced construction risk and project cost. DEEP FOUNDATIONS • MAR/APR 2020 • 69
