Analysis On The Dynamic Soil-Pile-Cap-Machine System Interaction

The objective of this paper is to investigate the analysis of dynamic soil-pile-cap machine system interaction in the background of the practical project. The dynamic characteristic parameters of this system are studied using the finite element method. In view of the system complexity, it is difficult for a number of previous methods to consider the embedded cap effects on the dynamic pile-soil interaction system. As a result, the dynamic impedance of a pile group with embedded cap was rarely reported. The investigation in this paper has an important academic significance on the insight into the dynamic pile foundation with embedded cap as well as applied value in the engineering practice.For the purpose of determining the basic problems such as the computed field and the mesh sizes in the finite element method, the paper first deals with the problems of a semi-infinite soil domain with radiation damping and material damping through the transient response of a single pile, which are used in the finite element method. The paper investigates the parameters of single piles, pile groups and pile groups with embedded caps in the layered media and compares the dynamic impedance of pile foundations obtained from the finite element method with that from other simplified methods. The results in this paper are valuable to the pile groups with embedded cap.Second, based on the parameter study of pile foundations, the corresponding relationship between the soil property parameters needed in the finite element method and the engineering parameters of soil in Dynamic Machine Foundation Design Code(for short of Dynamic Code) is presented in this paper. This relationship is for the use of the practical project in this paper as well as for the reference to other engineering projects.Finally, this paper performs a dynamic analysis on a large-scaled paper machineadopting the substructure method based on the dynamic impedance of the pile foundation gained by the finite element method and by the Dynamic Code method respectively. The results show that the dynamic impedance value from the Dynamic Code method is higher than that from the finite element method. It is possible that the vibration of actual foundations exceeds the allowable value, so the design according to the Dynamic Code perhaps is not safe. Therefore, it is necessary to pay an attention to this fact. The finite element results in this paper can provide quantitative estimates for engineers, which has an important applied value.