Abstract
To explore the dynamic characteristics and influencing factors of immersed tunnels under the action of earthquakes, 5 groups of shaking table model tests were carried out. Three different site conditions (unsaturated sand site, homogeneous saturated sand site, and nonuniform site), structural stiffness, and seismic wave input direction were considered. By comparing the above influencing factors, the seismic response law affecting the immersed tunnels was obtained. The test results show that, under the action of horizontal earthquakes, the liquefaction of sand and the larger tunnel stiffness may influence the acceleration development of the soil layers; seismic wave input directions affect the excellent frequency and frequency range of the soil layers, and the liquefaction of sand and large structural stiffness change the shape of the Fourier spectrum curve of the soil layers; site conditions, structural stiffness, and seismic wave input direction have a significant effect on the internal forces of tunnels. Normally, the strain in the heterogeneous soil layer under the horizontal seismic wave input is the largest, and the peak strain of the upper side of the tunnel side wall and center column is larger than the lower part, while the mechanism of structural damage caused by vertical earthquakes is different.
Highlights
At present, the main methods for tunnel construction include shield tunneling and immersed tube [1, 2]
Immersed tunnels in the water environment, located in a complex environment, are prone to damage under large dynamic loads, especially earthquake loads
There are three methods widely used to study the seismic performance of immersed tunnels, namely, prototype observation, theoretical analysis, and experimental research
Summary
The main methods for tunnel construction include shield tunneling and immersed tube [1, 2]. There are three methods widely used to study the seismic performance of immersed tunnels, namely, prototype observation, theoretical analysis, and experimental research. Shaking table model tests could reproduce the seismic process of underground structures rapidly, enabling researchers to intuitively understand the seismic response law and failure mechanism of underground structures. In order to understand the dynamic characteristics and influencing factors of the immersed tunnels under earthquake action, taking the Hong Kong-Zhuhai-Macao submarine immersed tunnel project as the research background, a scaled model shaking table test was carried out on the immersed tunnels. In order to explore the seismic response law and influencing factors of immersed tunnels, factors such as unsaturated sand (dry sand) site, saturated sand site, longitudinal nonuniform site, tunnel stiffness, and ground motion input were considered, with 5 groups of tests designed. In order to obtain the seismic response law of different immersed tube tunnel stiffness, two tunnel models with different stiffness were made in this experiment
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