Research on seismic response of new lining structured of shallow double-arch tunnels under unsymmetrical pressure

A physical test model of a new lining structure for a shallow double-arch tunnels under unsymmetrical pressure with a scale of 1:20 was designed and manufactured. Kobe seismic waves and EI seismic waves were selected as the loading waves and a large-scale shaking table test was carried out. The acceleration and dynamic strain response of shallow double-arch tunnels under unsymmetrical pressure under different seismic wave types and seismic intensities are studied. The results show: Under different seismic wave excitations, only the horizontal acceleration amplification factor of the left-hole vault, right-hole invert and the top right of the mid-partition is less than 1, and the horizontal acceleration amplification factors of other measurement points are all greater than 1. The measurement points with relatively large horizontal acceleration response are the left-hole shoulder, the top left of the mid-partition, the right-hole vault and shoulder; The overall response of the right half-arch of the left-hole is greater than the left half-arch of the left-hole, and the overall response of the left half-arch of the right-hole is greater than the right half-arch of the right-hole. The measured points in the left half-arch of the left-hole and the right half-arch of the right-hole have small differences in acceleration response; The effects of Kobe wave on horizontal acceleration and vertical acceleration are greater than EI wave, and the average value of the vertical acceleration response of the lining is greater than the average value of the horizontal acceleration response. With the increase of seismic intensity, the larger the acceleration amplification factor is, the greater the increase is; Under the action of different seismic waves, the seismic wave excitation has a greater impact on the dynamic strain response of the left-hole, and less impact on the right-hole. Among them, the strain value of the left-hole shoulder, left-hole invert and the top left of the mid-partition is much larger than the other measurement points, the trend of the right-hole is relatively gentle, and the strain values of the shoulder are slightly larger. The research conclusions have certain guidance and reference value for the seismic design of shallow double-arch tunnels under unsymmetrical pressure.