Estimation of bearing capacity of driven piles using numerical modeling

Abstract

Pilling is a blend of art and science. While choosing a suitable pile type and the installation method lie in the artistic aspect, scientific dimensions allow engineers to study the behavior of installed elements under different types of loading. The nature of the interaction between a pile and the soil it contacts is significantly influenced by the method of installation used. This interaction cannot be accurately predicted based solely on the physical properties of the materials involved. Different methods are used to determine the bearing capacity of piles, including static equations, dynamic equations, empirical methods, numerical methods, computer software programs, and pile static load tests. However, it is important to note that each of these approaches may yield different values for the bearing capacity of piles, and rarely do any two methods produce identical computed capacities. According to Randolph M. F. (1992), achieving precise estimates of axial pile capacity in various soil types is a challenge and often results in a margin of error of approximately ±30% During the last few decades, there has been swift and substantial progress in the analytical methods employed in pile design. This advancement not only validated traditional empirical approaches but also led to their replacement with more robust theoretical foundations. In intricate geotechnical projects, when dealing with complex load combinations or substantial interaction with adjacent structures, engineers often turn to the Finite Element Method (FEM) for analysis. However, an exception to this trend is observed in the design of driven piles or soil- displacement piles, where a different approach is typically employed to determine factors such as pile capacity and performance. In the modeling of displacement piles, it is essential to compile the installation effects resulting from different installing techniques with the most applicable constitutive model to obtain an accurate result by simulating real soil behavior. With the evolution of computational power, different numerical techniques can be employed successfully in standard FE analysis using soil parameters obtained from cost-effective site investigations to lead to a more realistic load- settlement response for driven piles or soil-displacement piles.