Experimental Investigation of Vertical and Lateral Bearing Behaviors of Single Piles

Pile foundations may be subjected to a combination of vertical and lateral loads that are commonly not applied simultaneously. Model tests of six instrumented single piles embedded in remolded loess, in which self-developed equipment was used to carry out different loading sequences of vertical and lateral loads, were performed. The test results indicate that the preapplied lateral load can cause a decrease in the average skin friction of the pile shaft within 13 times the pile diameter below the ground surface, as well as an increase in the pile end resistance. The settlement of the pile top increases with the increase in the preapplied lateral load, and its rate of change increases with increasing vertical load and increasing preapplied lateral load. With the increase in the preapplied vertical load, both the horizontal displacement of the pile at the measuring point and the maximum bending moment of the pile shaft decrease. The location of the maximum bending moment of the pile shaft is between 2 and 4 times the pile diameter below the ground surface, which approaches the ground surface when the preapplied vertical load increases. The preapplied vertical load can increase the ultimate horizontal bearing capacity of the pile.