Tunnels are major projects of infrastructure for civil purposes. Surface settlements can occur by tunneling processes. This settlement can be predicted by different techniques like empirical methods and finite element methods which represent a simulation for real field measurement results. Most empirical solutions don’t take into account the influence of changed soil densities upon ground deformation during tunneling excavations. The finite element analysis (FEA) reflects the parameters of strength and stress of the variant of densities of sandy soil. The tunneling process requires the study of great soil-structure interaction problems. In this paper, FEA is utilized to predict the ground displacements that happened by the tunneling process. For judging the reliability of the numerical analysis, a case history along the Greater Cairo Metro tunnel is studied. The ground displacements obtained by the surface displacement equation (SDE) produced by Peck and Schmidt (1969) are represented and discussed. Field measurements are compared with settlements obtained by both FEA and SDE. The ground displacements obtained by SDE are compared by those obtained by FEA at variant densities of sandy soil. The main target is to estimate a suitable formulation that represents the changed cases in sand densities in SDE compared with FEA. The results showed that the changed soil densities in the sand which are disregarded in SDE take an important significance upon the surface displacements that occurred by the tunneling in sand soil.
|
