S - Kam Ng PhD Dissertation Final.pdf - Digital Repository of CCEE ...

31.1.2. Pile design and verification methodsThe main challenge associated with the deep foundation design is the ability toaccurately predict and verify pile resistance, which primarily stem from significant variationsof soil properties. Furthermore, pile resistance can be estimated using static analysismethods, dynamic formulas, and dynamic analysis methods. Because of the empirical natureof some of the methods combined with the influence of variation in soil parameters, theresistance of a pile calculated based on different methods may differ significantly even if thedifferent methods follow the same analysis concept (e.g., static analysis methods).Driven pile foundations are normally designed using the static analysis methods.Static analysis methods approximately estimate the pile resistance based on soil propertiesobtained from both laboratory and in-situ soil tests. However, the static analysis methodscannot be used to verify the estimated pile resistance during pile driving. In recognizing thisdeficiency, the pile resistance is usually verified by an expensive and time consumingapproach known as the static load test specified in the American Society for Testing andMaterials (ASTM) as ASTM D 1143: Quick Load Test Method. In addition, pile drivingformulas, which are formulated from the principle of conservation of work done, areconventionally used for verifying the pile resistance and introduce a means to limit the piledepth—this practice is often referred as construction control. Unfortunately, pile drivingformulas produce unimpressive and conservative resistance (Coduto, 2001).As a result, alternative methods, such as dynamic analysis methods, are desired toimprove the pile design and verification. With the advent of digital computers, dynamicanalysis methods have not only gained popularity and but also continue to be advanced. Theyare now used as routine methods for verifying pile performances and have been incorporatedinto a standard specification for testing deep pile foundations in the American Society forTesting and Materials (ASTM), ASTM D-4945. The advantages of using the dynamicanalysis methods are as follows: (1) give accurate pile resistance estimation; (2) evaluatetime dependent pile resistance; (3) provide pile driving control; (4) detect pile damage and