Dynamic response analysis of liquefiable ground due to sinusoidal waves of different frequencies of shield construction

Vibration induced by shield construction can lead to liquefaction of saturated sand. Based on FLAC 3D software, a numerical model of tunnel excavation is established and sinusoidal velocity loads with different frequencies are applied to the excavation face. The pattern of the excess pore pressure ratio with frequency, as well as the dynamic response of soil mass under different frequency loads before excavation, is analyzed. When the velocity sinusoidal wave acts on the excavation surface of the shield tunnel with a single sand layer, soil liquefaction occurs. However, the ranges and locations of soil liquefaction are different at different frequencies, which proves that the vibration frequency influences the liquefaction location of the stratum. For sand-clay composite strata with liquefiable layers, the influence of frequency on the liquefaction range is different from that of a single stratum. In the frequency range of 5–30 Hz, the liquefaction area and surface subsidence decrease with an increase in vibration frequency. The research results in this study can be used as a reference in engineering practice for tunneling liquefiable strata with a shield tunneling machine.