Interpretation of Load-Settlement Curves from Graphical Methods

Abstract

Bearing capacity of pile depends mainly on the type of soil through which it rests and on the method of installation. Many empirical and analytical formulae developed based on the field and laboratory experiments to estimate the pile group bearing capacity. The present investigation is carried out to get the load-settlement characteristics of different configurations of pile groups, such as 1 × 1, 2 × 2 and 3 × 3. In many projects, some of the manufactured piles are loaded to determine the pile bearing capacity. This is the most reliable way to determine the pile capacity. However, it is not easy to determine the point where the pile has reached its ultimate capacity on the load-settlement curve. By using different graphical methods, the ultimate bearing capacity is calculated from load-settlement data. Among these methods, there are considerable differences between the graphical ultimate bearing capacities of the piles which decrease to 35% for the piles loaded up to the collapse load and increases up to 120% for the piles loaded to the failure load. Improvement ratio and settlement ratio are calculated using load-settlement curves. Model plate load test is used to determine the load-settlement curves. It is time and cost efficient, easy to perform and reliable. Experiments are conducted on dry, clean and poorly graded sand. Steel pipe piles of length 30 cm, diameter 2 cm, 2.5 cm are used in this experiment. The spacing between the piles is taken as 3d.