The Characteristics of Seismic Response on Hard Interlayer Sites

Jie Su,Yafei Wang,You Zhou,Zhenghua Zhou,Liu Chen,Qing Dong,Xiaojun Li,Yuping Li

doi:10.1155/2020/1425969

Abstract

Based on the engineering geological data of a nuclear power plant site, nine engineering geological profiles were created with hard interlayers of different thicknesses. The equivalent linearization method of seismic motion segment-input used for one-dimensional nonlinear seismic response analysis was applied to study the effect of the interlayer thickness on the peak acceleration and the acceleration response spectra of the site seismic response. The results showed that there was an obvious influence of hard interlayer thickness on site seismic responses. With the increase of hard interlayer thickness, the site nonlinear effect on seismic responses decreased. Under the same thickness of the hard interlayer, the nonlinear effect of the site was strengthened with the higher input peak acceleration. In addition, the short-period acceleration response spectrum was found to be significantly influenced by the hard interlayer and showed that the longer the period, the less influence of the hard interlayer on the acceleration response spectrum coordinates. Moreover, the influenced frequency band was wider with the increase in the thickness of hard interlayer.

Highlights

According to the code for evaluation of seismic safety for engineering sites of China [40], the surface of the bedrock determined by drilling or the surface of the layer with the shear wave velocity not less than 700 m/s should be used as the input interface of ground motion for class-I site when establishing the onedimensional site seismic response analysis model. erefore, we chose the interface at the depth of 337.5 m as the interface of input ground motion, which is called the computational basis of the model
Nine one-dimensional analysis models were established in accordance with the engineering geological data of a nuclear power plant site for the site response analyses utilizing the equivalent linear method. e numerical results are as follows: (1) e peak accelerations on the top of the hard interlayer are less than the input peak accelerations, while the peak accelerations on the site surface are greater than the input peak accelerations under different input seismic motions and hard interlayer thicknesses
(2) With the increase in the hard interlayer thickness, the S/T generally shows a gradual trend of increase, which indicated that the increase in the hard interlayer thickness reduced the nonlinear effect of the site

Summary

Analysis models

E model 9 corresponded to the actual soil layer profile, while the thickness of the hard interlayer of model 8 is 126.7 m with the original volcanic breccia of layers 14 to 42 was replaced by silty clay. E shear wave velocities of the replacement silty clay layer were determined according to equation (1), which was based on the statistical regression of the in-situ test shear wave velocity data. Models are provided in Table 4. e shear wave velocities of the replacement silty clay layer were determined according to equation (1), which was based on the statistical regression of the in-situ test shear wave velocity data. e statistical data

Ratio Ratio

Conclusions