Dynamic Analysis Of The Cooperation Between Dynamic Basis And Foundation

The structure and foundation are considered separately in common dynamic machine foundation design, and the commonly design software MFSAP do not consider the foundation either. But actually, the soil works together with the structure, and the cooperation of the two under dynamic loads is widely accepted by designers. Based on a practical project, this article studied the dynamic characteristics of the cooperation, using finite element analysis software ANSYS.A lot of literature about the cooperation of the structure and foundation are read to analyze the research status and shortcomings of dynamic machine foundation home and abroad. Based on some assumptions and former theoretics, the dynamic parameters of natural foundation and pile foundation are calculated.In the study of the dynamic parameters of soil, the current theory mass-damp-spring model and elastic half-space model is introduced, and the dynamic parameters of natural foundation is calculated by practical elastic half-space model. These parameters are compared with those gained by theories in "dynamic machine foundation design" to obtain reasonable dynamic parameters. In the study of parameters with pile foundation, the single pile vibration differential equation and the definition of stiffness are used to obtain the stiffness and damping of single pile. Considering the group effect, the dynamic parameters of pile foundation are obtained. Then the results are compared with the parameters in actual pile test, and the relationship between the two parameters is gained to provide a reference for the back.A lot of work is made in finite element calculations on the cooperation of dynamic basis and foundation. Three kinds of finite element model are built. The first model does not consider the cooperation of basis and foundation, the second model consider the cooperation in natural foundation, and the third consider the cooperation in pile foundation. Using the relevant stiffness and damping ratio parameters, the spring element is used to simulate the soil and pile foundation, the three-dimensional solid element is used to simulate the superstructure and its foundation, the spring element is combined with contact point, and the finite element dynamic calculations is conducted. Comparing the results of model analysis and the vibration linear displacements, it can be seen that the cooperation of basis and foundation is very important. In addition, the resonance region can be speculated by the frequency of maximum vibration linear displacements in the process of machine operation, and make external incentives far away from these areas. Some references can be gained to design and optimize in actual project.