TY  - JOUR
AU  - Zhou, Jiamei
AU  - Li, Ruihan
AU  - Hunag, Ke
AU  - Cui, Kaiqi
AU  - Yue, Feixiang
PY  - 2024
TI  - Study on the Dynamic Response of Large Span Railway Tunnel Portal Based on Extension Theory
JO  - Chinese Journal of Underground Space and Engineering
SN  - 1673-0836
SP  - 625
EP  - 635
VL  - 20
IS  - 2
AB  - There are shallow buried bias and broken surrounding rock in the tunnel portal section. In order to explore the dynamic response law of the tunnel portal section under the action of earthquake and give the quantitative evaluation index of safety, a numerical model is established based on the No.6 tunnel of Yawan high-speed railway. Four seismic waves of artificial synthetic wave, EI wave, KB wave and WL wave are input respectively. Based on the extension theory, an extension matter-element model is established. The results of four safety evaluation indexes of bending moment, axial force, relative displacement and acceleration of the tunnel portal section under the most unfavorable seismic wave are obtained by numerical simulation method, and the safety evaluation of the No.6 tunnel portal section of Yawan high-speed railway is carried out with quantitative indexes. The seismic fortification length is proposed. At the same time, the dynamic response law of No.6 tunnel portal section of Yawan high-speed railway under different seismic waves is also analyzed. The results show that; (1) Under the action of Yawan artificial wave, the dynamic response degree of each evaluation point of the tunnel is about 1.2 times that of the other three natural waves; (2) The four evaluation indexes calculated by each seismic wave have basically the same variation law along the longitudinal direction. The peak values of axial force and bending moment appear at the arch foot of the spandrel arch, and the peak values of relative displacement occur from the inverted arch to the vault line at the entrance of the cave. The peak time of the evaluation index is slightly lagging behind the corresponding time of the peak acceleration of the seismic wave. (3) Under the action of YW wave, the seismic fortification length of No.6 tunnel portal section of Yawan high-speed railway is 45~55 m, which is 3.5~4 times of the tunnel diameter. The research results can provide reference for determining the seismic fortification length of tunnel portal section by quantitative index.
UR  - https://doi.org/10.20174/j.JUSE.2024.02.29
DO  - 10.20174/j.JUSE.2024.02.29