Abstract: Seismic liquefaction of sand will give rise to the failure of foundation and structural damage. Discriminating liquefaction of the construction site is of vital importance. Liquefaction discrimination methods in specifications in China and abroad are simple and practical, yet still of some limits. In this paper, we performed numerical analysis on the seismic liquefaction characteristics of typical borehole soil layer of a shield tunnel project in Kanapuri River of Bangladesh using the FINN module of FLAC^3D. We applied a reasonable seismic wave after the balance of gravity and water pressure and calculated the maximum excessive pressure ratio of each unit in the calculation process. If the maximum excessive pore pressure ratio is equal to one, the soil is liquefied at this position; if the maximum excessive pore pressure ratio is less than one, the soil is not liquefied. Calculation result revealed that the maximum excessive pore pressure ratio of some parts of soil is equal to one and other parts less than one. The result indicated that seismic liquefaction occurs in the soil layer in this area, and the liquefaction range is different at different locations. The result is consistent with the discriminant results of specification methods.

Key words: anti-seismic safety of shield tunnel, liquefaction discrimination, FLAC^3D, FINN module, excessive pore pressure ratio