The influence of seepage forces on ground reaction curve of circular opening

When a tunnel is excavated underneath a groundwater table, groundwater flows into the tunnel and consequently, seepage forces act on the cross-section of the tunnel. Such seepage forces significantly affect the ground reaction curve, which is defined by the relationship between the internal pressure and displacement of the tunnel wall. From a practical point of view, a simplified analytical solution of the ground reaction curve accounting for the seepage forces with steady-state flow was developed in this study based on ground reaction curve theories from earlier studies. The simplified analytical solution derived in this study was validated by numerical analysis. The changes in the ground reaction curve according to various ground and groundwater table conditions were investigated. Finally, the simplified analytical solution of the ground reaction curve developed in this study can be used for approximate design of circular openings such as tunnels excavated underneath a groundwater table with seepage forces.