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Improved Integral Response Displacement Method for Shallow-buried Tunnel Portal Section in Highly Seismic Regions
(1. Key Laboratory of Transportation Tunnel Engineering, Ministry of Education, Southwest Jiaotong University, Chengdu 610031;2. National Engineering Research Center of Geological Disaster Prevention Technology in Land Transportation, Southwest Jiaotong University, Chengdu 610031; 3. China Railway Eryuan Engineering Group Co., Ltd., Chengdu 610031)
Abstract In order to improve the seismic performance of the tunnel portal structure under strong earthquakes, based on a pipeline tunnel project in a high-intensity seismic area, the error influencing factors of the integral response displacement method in seismic calculation of the tunnel portal section are studied. The structural displacement amplification coefficient is introduced, and an improved integral response displacement method suitable for structural seismic calculation of the tunnel portal is proposed. Furthermore, the improved calculation method is verified based on case analysis. The results show that the error in the seismic calculation of the tunnel portal section using the integral response displacement method is mainly caused by the relative displacement between the top and the bottom of the tunnel at the tunnel portal section, and it can be corrected by introducing a structural displacement amplification coefficient. The structural displacement amplification coefficient is positively correlated with the front slope angle of the tunnel portal and the seismic intensity, but negatively correlated with the slope height and relative burial depth. The deviation of amplification coefficient in different levels of surrounding rock is less than 10%, and the influence of surrounding rock conditions on it can be ignored. The error of the improved integral response displacement method under 0.6g seismic motion is basically less than 10%, which has higher accuracy than the integral response displacement method and can be applied to seismic calculation of the tunnel portal section.
Abstract：
In order to improve the seismic performance of the tunnel portal structure under strong earthquakes, based on a pipeline tunnel project in a high-intensity seismic area, the error influencing factors of the integral response displacement method in seismic calculation of the tunnel portal section are studied. The structural displacement amplification coefficient is introduced, and an improved integral response displacement method suitable for structural seismic calculation of the tunnel portal is proposed. Furthermore, the improved calculation method is verified based on case analysis. The results show that the error in the seismic calculation of the tunnel portal section using the integral response displacement method is mainly caused by the relative displacement between the top and the bottom of the tunnel at the tunnel portal section, and it can be corrected by introducing a structural displacement amplification coefficient. The structural displacement amplification coefficient is positively correlated with the front slope angle of the tunnel portal and the seismic intensity, but negatively correlated with the slope height and relative burial depth. The deviation of amplification coefficient in different levels of surrounding rock is less than 10%, and the influence of surrounding rock conditions on it can be ignored. The error of the improved integral response displacement method under 0.6g seismic motion is basically less than 10%, which has higher accuracy than the integral response displacement method and can be applied to seismic calculation of the tunnel portal section.
SHEN Yusheng1,
2 ZHAO Helin1 ZHU Zhengchao1 YI Penghao1 LEI Long3 SU Wei3
.Improved Integral Response Displacement Method for Shallow-buried Tunnel Portal Section in Highly Seismic Regions[J] MODERN TUNNELLING TECHNOLOGY, 2023,V60(5): 78-87
2023, Vol. 60 