Parameters Analysis of the Covering Soil of Tunnels Constructed In Liquefiable Soils

Earthquake and its catastrophic failures has been one of the disturbance worry of Civil Engineers. In geotechnical science, liquefaction is one of the most important phenomenons induced by earthquake. A change in pore water pressure follows a change in effective stress, and in a critical state in which pore water pressure equals the total stress in soil particles, soil strength is suddenly lost and liquefaction occurs. This phenomena cause destruction of structures constructed above ground surface or underground. In case of constructing underground structures or passing a tunnel through weak or compressible soils, with increase in forces and moments surrounding the structures leading to liquefaction, may impose damages to adjacent structures or soils. In this paper a tunnel passing through a soil media with liquefaction potential is modeled. After static equilibrium, dynamic analyses are performed. Using liquefaction modeling and measurement of induced forces and moments of covering soil of the tunnel, parameters such as water bulk modulus, groundwater level, and porosity are investigated. The results showed that the above mentioned parameters have considerable affects on variation of effective stresses, induced forces, moments and surface dilation of the covering soil of the tunnel.