Analysis on seismic influence factors of underground electric substation foundation pit enclosure structure

Based on the 500 kV underground electric substation foundation pit enclosure structure of Shanghai World Expo,a modeling calculation was done with the fast largangian analysis of continua in dimensions(FLAC3D,and some major influence factors on the foundation pit enclosure structure and the seismic stability of the surrounding soil were studied.The factors included four aspects,namly the nature of the surrounding soil of the pit,the properties of the foundation pit enclosure structure,the peak acceleration of the seismic waves and the dominant frequency of the seismic wave.The results show that the vibration of the pit deformation is constrained by the surrounding soil,that the better the nature of the soil,the more obvious the constraints,and the smaller the vibration deformation,that the pit has also little influence on the vibration of the surrounding soil,that the strength of the underground substation has an effect on the vibration deformation of the whole pit,but the influence is not obvious,that the internal force value of the enclosure structure and the ability of damage resistance increase with the material strength of the enclosure structure,that if the seismic wave amplifiee its peak acceleration,its energy will amplify as well as the deformation of the pit,but internal force value has no obvious change,and that under the constraint of the surrounding soil,the pit shows no corresponding natural vibration characteristic.These conclusions may provide reference similar circular foundation pit seismic design.