Behavior of Laterally Top-Loaded Deep Foundations in Highly Porous and Collapsible Soil

Abstract

Problems associated with horizontal loading in foundation structures often occur when the surface soil has particular characteristics like the unsaturated, porous, and collapsible soils that are very common in Brazil. In the state of São Paulo, more precisely in the region of Campinas, the occurrence of such soils is detected in several places. For this reason, this work was conceived for the purpose of assessing the performance of four types of deep foundations subjected to horizontal loading via analysis of the load versus horizontal displacement curve and determination of the horizontal reaction coefficient of the soil (nh). To accomplish this, load tests were carried out with bored piles, continuous flight auger piles (CFA), steel piles, and belled caissons at the Experimental Site of Foundations at the State University of Campinas—Unicamp, Campinas, São Paulo, Brazil. The tests were performed under soil conditions of natural moisture and after 48 h of flooding. The results showed a large drop in parameters of soil resistance due to flooding—an approximately 50% drop on average for the ultimate load and 70% for the horizontal reaction coefficient of the soil.