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| Longitudinal seismic response analysis of long tunnels based on random field model of strata parameters |
| YU Haitao1, HE Shuang2, LI Pan2,3*, LI Shuai4, CHEN Fengjun5, WANG Xinxin5
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1. Key Laboratory of Geotechnical and Underground Engineering of Ministry of Education, Tongji University, Shanghai 200092, China;
2. Department of Geotechnical Engineering, Tongji University, Shanghai 200092, China;
3. School of Rail Transportation, Soochow University, Suzhou 215131, Jiangsu, China;
4. China Machinery Industry Information Institute, Beijing 100037, China;
5. Shanghai Construction Group Co., Ltd., Shanghai 200080, China |
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Abstract Seismic responses of tunnel structures are closely related to the surrounding strata properties. Currently, long tunnel construction develops fast and the tunnel length may reach up to several or even scores of kilometers. The strata parameters along the tunnel have significant spatial variability and correlation. However, the strata data used in the longitudinal seismic design of the tunnel was based on limited borehole data, and thus the random field characteristics of strata parameters between the boreholes have not been considered yet, or at least not well addressed. In this paper, a stochastic field model describing spatial variability and correlation of strata parameters was established based on the random field theory, and the covariance matrix decomposition method was used to generate random field distribution of strata parameters, which were employed into the simplified three-dimensional finite element model to characterize the dynamic interaction between stratum and structure. A series of simulation cases of tunnel longitudinal seismic response considering the influence of random field of stratum parameters were carried out to study the influence of horizontal correlation distance, variation coefficient and mean value of stratum on the seismic response of tunnel structure. Results indicated that: the correlation distance, variation coefficient and mean value all had a significant impact on the seismic response of the structure, and the change of horizontal correlation distance and mean value had a negative influence on the seismic response of the structure while the coefficient of variation had a positive influence. The influence of variation coefficient on the structural response was significantly greater than correlation distance; compared with the mean field without consideration of the randomness, the random field could significantly amplify the moment response amplitude of the tunnel structure by about 80%, and the mean field results would lead to unsafe design under the confidence level of 0.005.
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Received: 18 June 2020
Published: 20 September 2020
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