Condition monitoring of piled foundations
In this thesis a brief history of dynamic pile analysis methods and the associated background theory are presented. In addition an unpublished rigorous mathematic proof of the Case method and new general theoretical model for dynamic pile analysis, developed as the Aberdeen method, are given. The dynamic and static response of model concrete piles in dry sand to impact and static loads have also been investigated experimentally and the results are reported in this thesis. Pile response has been found to be crucially dependent on the damping in the system. The method of modal analysis has been found to be the best approach to determine the damping factor of both the onshore and the offshore piles and is discussed in detail. A theoretical relationship between the initial and the reflected stress waves and the dynamic point resistance is used to calculate the force-penetration relationship and nonlinear parameters for the special case of pile points on dry sand. The shock relation, equations of motion and compatibility of the dynamic measurement at pile top are given by the Aberdeen method. This method gives a mathematical description of the behaviour of impact response which has not been achieved in either the Case or the TNO method. At present, the Case and TNO methods are used to investigate the integrity of piled foundations by means of the impact concept. This thesis introduces a third method, the J-integral method in the study of piled foundation. In addition, the thesis also gives a theoretical explanation to the TNO method which have not been provided elsewhere.