An estimation of subsurface settlement due to shield tunneling

An empirical method based on the normal distribution function is proposed to estimate the magnitude and extent of subsurface settlement associated with shield tunneling. Based on field measurement data, empirical relationships are established between surface and subsurface settlement troughs. Assuming the surface settlement due to tunneling could be obtained by the analytical, numerical, or field monitoring method, based on these relationships, the range of subsurface-settlement can be easily estimated. Twenty three sets of measured subsurface settlement profiles associated with tunneling with open, slurry and earth-pressure-balance shields are compared with the predicted curves. It is concluded that the application of normal probability function can be extended to estimate the subsurface settlement due to shield tunneling. The width of the subsurface settlement trough decreases with increasing depth, and the maximum subsurface settlement increases with increasing depth. The subsurface settlement curves calculated using the proposed method are in fairly good agreement with field measurements for various types of shield machines, depths and diameters.