Experimental Study On Vibration Characteristics And Dynamic Response Of Spring Vibration Isolation Foundation On Site

With the continuous improvement of the quality of life of our residents,social electricity consumption is growing,large capacity turbine generator unit are more widely used in the production of power plants.Turbine generator unit belongs to dynamic machines,when the unit is working,it will inevitably generate a dynamic load to its foundation,there are certain characteristics of turbine foundation in design compared with other structural foundations.Spring vibration isolation foundation can effectively reduce the transmission of vibration energy of the power machine,which is more and more favored by the power plant construction.In previous studies,a large number of model tests and numerical simulations have been done on the vibration isolation foundation in China,but the field test for vibration isolation foundation is very rare.The foundation model test is limited by the space or the loading capacity of laboratory.It is difficult to accurately meet the similar conditions in the model design,which has some limitations.Numerical simulation will produce some inevitable errors caused by subjective factors.In order to study the vibration characteristics and dynamic response of spring vibration isolation foundation in practical application,this paper takes the spring vibration isolation foundation of steam turbine generator set in a large thermal power plant as an example,a field experiment on the foundation was carried out.The full text reads as follows:(1)After the completion of all construction of the foundation,unit and related equipment layout is completed,we conducted a self-vibration test of the turbine foundation in the field.Using the hammering test,the natural frequency,vibration mode and damping ratio of the foundation are obtained.(2)Under the maximum operating conditions of the unit,we arranged the sensors on the soleplate,the value of vibration velocity,the value of vibration displacement and the velocity spectrum of the soleplate are obtained by using the signal acquisition device.The dynamic response of the foundation is evaluated by referring to the domestic and foreign evaluation standards.(3)Under the working condition of stable operation of the unit,the working conditions of the unit is as excitation conditions,the vibration parameters such as the vibration modes and modal damping of the foundation structure are obtained.(4)Under different operating conditions of the unit,the displacement of the bearing pedestal is collected,so we can study the influence of different conditions on the displacement of the bearing pedestals.The results can be summarized as follows.Most of the natural frequencies of the foundation are far away from the frequency of normal operation of the turbine unit,which reduces the resonance.By analyzing the vibration spectrum of the foundation,it is found that the vibration energy corresponding to the low-frequency band is obvious.In the working mode test of the foundation,the vibration of the low-pressure cylinder is highlighted,it is recommended to pay close attention to the vibration of this position.We monitored the vertical displacement of the bearing pedestals in the stable operation of the unit,comparing the displacements of bearing pedestals under different working condition,the vacuum suction has the greatest influence on the displacement of foundation and it is suggested to pay attention to this condition.