Shaking table tests on seismic liquefaction characteristics of soil surrounding tunnels in saturated loess stratum

Based on the previous numerical and theoretical analyses, a series of shaking table tests with scale of 1∶20 for seismic liquefaction analysis of saturated surrounding loess are carried out to simulate the loess section of a tunnel under construction on the Lanzhou-Hezuo Railway in China. The results show that the soil–structure interaction significantly increases the liquefaction potential of the soil near the tunnel linings, and the surrounding soil will produce liquefaction before the soil of the same level when subjected to seismic loads. When the peak acceleration of seismic loads ${a_{{\text{max}}}}$ is minor (i. e., ${a_{{\text{max}}}}$ = 1.0 m/s²), the peaks of dynamic shear stress ${\tau _{{\text{d, max}}}}$, dynamic pore water pressure ${U_{{\text{d, max}}}}$, and acceleration ${a_{{\text{p, max}}}}$ near the lining structure are larger than those far away from the lining at the same level height, and have obvious amplification effects. With the increase of ${a_{{\text{max}}}}$ to near the liquefaction stage of surrounding soil, the amplifying effects of dynamic pore water pressure ${U_{\text{d}}}$ are obvious, while the amplifying effects of shear stress ${\tau _{{\text{d, max}}}}$ and acceleration ${a_{{\text{p, max}}}}$ decreases or disappear. In particular, the variation characteristics of the acceleration of the surrounding soil reveal the deficiency of the previous numerical simulations.