AcadeMax field tests uplift piles

Uplift piles are buried anchors: they keep basements, towers, and other structures from being pushed upward by groundwater or other forces. A new 2026 AcadeMax paper studies how those piles behave when a weak soft-soil layer sits between stiffer soils in Hangzhou. (academax.com) The paper is titled “Study on the influence of soft soil interlayer on the mobilization of side friction resistance of bored piles under uplift loading.” It is listed in *Journal of Ground Improvement*, volume 8, issue 1, pages 1-12, with Han Tongchun, Shi Zhanbin, Wang Quanzhen, Linghu Zhibo, and Yu Jindi as authors. (academax.com) The basic mechanism is simple: an uplift pile resists pull mainly through side friction, the grip between the pile shaft and surrounding soil. If one layer is soft, that grip weakens in the soft layer itself and can also disrupt how nearby stiffer layers share the load. (academax.com) Han and co-authors said they combined field-test data from uplift piles in “typical soft soil interlayer distribution areas of Hangzhou” with numerical simulation. Their goal was to track how soft interlayers change the mobilization of side friction in bored piles under uplift loading. (academax.com) The headline result is that soft layers cut performance twice. The layer has low side friction on its own, and it also affects the side friction resistance of adjacent stiff soil layers, according to the abstract. (academax.com) The simulations add a second finding: when the soft interlayer lies deeper, the drop in its side friction resistance becomes more pronounced. The paper says that deeper soft layers lead to a gradual decrease in the pile’s ultimate uplift bearing capacity. (academax.com) That does not mean every movement gets dramatically worse. The abstract says the depth of the soft interlayer has a relatively minor effect on uplift displacement, even as ultimate bearing capacity declines. (academax.com) The design takeaway is practical rather than theoretical. The authors said their simulation work supports recommendations for plotting side-friction-resistance curves when engineers detect a soft interlayer, which can help evaluate bored-pile uplift capacity more accurately. (academax.com) That matters most in underground construction, where uplift piles are common in high-rise buildings, underground parking structures, and transmission-tower foundations. The paper frames soft interlayers as a site condition that can change stability calculations even when the pile type stays the same. (academax.com) Han Tongchun is listed by Zhejiang University as an associate professor in the College of Civil Engineering and Architecture, with research interests including foundation engineering and underground space engineering. The new paper keeps that focus on how layered ground conditions alter real foundation behavior. (zju.edu.cn) (academax.com)