Numerical Modeling of Tunnels and Lifelines in Liquefiable Grounds Under Seismic Loading

Earthquakes could have catastrophic impacts on tunnels and buried structures. Liquefaction phenomenon is one of the most destructive effects of earthquakes. Liquefaction results in decreasing effective stress and this consequently leads to decreases in shear strength of the soil. As a result, large deformation in both soil and buried structure occurs. Moreover, liquefaction causes soil boiling, lateral spreading, structure settlement and the uplift of buried structure. In many earthquake cases, uplift of the buried structure due to liquefaction was reported as one of the major damaging factors. This research sought to model earthquake induced uplift of buried structures including tunnels in the soil susceptible to liquefaction under seismic loading. Two dimensional finite difference modeling is employed to simulate centrifuge experiments. The UBCSAND model was adopted as constitutive model in numerical simulations. The modeling results are compared with the measurements of centrifuge experiment and the capabilities of the model to predict the liquefaction of soil around tunnels are assessed.