ESTIMATION OF ADDITIONAL LOAD ON A SHIELD TUNNEL DUE TO GROUND SWELLING BY THE RECOVER OF GROUNDWATER LEVEL

Abstract

 On a shield tunnel constructed in the soft ground whose groundwater level continues to recover, additional load is generated due to ground swelling. Therefore, it is important to estimate how much the additional load should increase in the future, when such a tunnel is maintained. In this paper, we detect this groundwater level recovering as the main factor of cracks in the tunnel with Fault Tree Analysis (FTA). Also, we clarify the mechanism of the additional load occurrence by two dimensional fully coupled seepage-stress FEM analysis. Furthermore, we predicted the future groundwater level by hyperbolic curve estimation method, and predict precisely when steel bars of a segment of this tunnel should yield.